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I've now read both papers (MBH and MM) myself ... I agree with this reviewer of MM's short paper to Nature:

"The technical criticisms raised by McIntyre and McKritrik (MM) concerning the temperature reconstructions by Mann et al (MBH98), and the reply to this criticism by Mann et al is quite difficult to evaluate in a short period of time, since they are aimed at particular technical points of the statistical methods used by Mann et al, or at the use of particular time series of proxy data. A proper evaluation would require to redo most of the calculations presented in both manuscripts, something which is obviously out of reach in two weeks time. Furthermore, both manuscripts seem to contradict each other in some basic facts. Therefore, my comments are based on my impression of the consistency of the results presented, but there is a wide margin of uncertainty that could be resolved only by by looking in detail into the whole data set and the whole software used by the authors. In general terms I found the criticisms raised by McIntyre and McKritik worth of being taken seriously. They have made an in depth analysis of the MBH reconstructions and they have found several technical errors that are only partially addressed in the reply by Mann et al."

There are certainly some technical holes and questions that Mann hasnt responded to adequately. M+M point out that Mann had given 390 TIMES the weighting for one series whose mean had shifted upwards than to another similar tree ring series that didnt. See page 5, the comment on the Sheep Mountain series. You dont have to be a climatologist or a statistician to see how weighting one sample 390 times another one is a great way to create "junk science".
The tree rings were correlatied with more modern and more accurate temperature readings in a biased way which could turn even 'random series' data into a hockey stick.

See:

http://www.uoguelph.ca/~rmckitri/research/fallupdate04/update.fall04.html

"We had pointed to the overwhelming weighting given to one hockey stick-shaped North American tree ring series (Sheep Mountain CA) as a result of the subtraction of the 1902-1980 mean. A comment by Mann et al. which we found interesting was that their PC1 did not just depend on Sheep Mountain, but 14 other sites had at least 25% of the contribution of Sheep Mountain.

We re-submitted in late March, adding a new paragraph showing that these 14 highly weighted sites in the PC1 were all from a group of specialized and controversial high-altitude bristlecone pine series, studied by Graybill and Idso (1993), exhibiting an anomalous 20th century growth spurt, which yields hockey-stick shaped growth series. Graybill and Idso stated that explicitly that the 20th century growth could not be explained by local or regional temperature; co-author Hughes in Hughes and Funkhouser (2003) said that the anomalous growth was a "mystery"."

... Possible solution to the mystery: Higher CO2 may indeed be showing up
in these series in increasing tree growth, thereby distorting tree rings as valuable temperature proxies.

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Other comments on the MM short paper submission to Nature:

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On August 4, Nature advised us that our submission would not be published. The main reason was that the issues raised are too technical to resolve in the now 500 word space available:

In the light of this detailed advice, we have regretfully decided that publication of this debate in our Brief Communications Arising section is not justified. This is principally because the discussion cannot be condensed into our 500-word/1 figure format (as you probably realise, supplementary information is only for review purposes because Brief Communications Arising are published online) and relies on technicalities that do not bring a clear resolution of the underlying issues.

This decision primarily reflected the views of the new reviewer, who stated:

Generally, I believe that the technical issues addressed in the comment and the reply are quite difficult to understand and not necessarily of interest to the wide readership of the Brief Communications section of Nature. I do not see a way to make this communication much clearer, particularly with the space requirements, as this comment is largely related to technical details.

This reviewer did not object to any of our findings per se. Readers may share our surprise that the matters raised are "too technical" for consideration in a science journal; additionally, whether or not the matters were of interest to a "wide readership" (and we believe that they are), potential defects in MBH98 affect Nature’s publication record and require disclosure.

Our old referees again commented on the difficulty of resolving who was right and who was wrong. Referee #2 (Referee #1 of the first round) remained sympathetic, and stated:

The amount of material, often contradictory, is simply too complex and lengthy to resolve all the rights and wrongs in a realistic length of time" Only a reader with several days to spare (longer if they are unfamiliar with the area), to chase references and probably the authors, could hope to come close to a full understanding of the arguments.

I started my original review by saying that I found merit in the arguments of both MBH & MM. To rewrite this, I believe that some of the criticisms raised by each group of the other's work are valid, but not all. I am particularly unimpressed by the MBH style of 'shouting louder and longer so they must be right'. "

It is absurd to thinking "global warming" has been "proved" because A FEW SMALL SAMPLES OF BRISTLECONE PINE showed anomalous growth in the 20th century, BUT THAT IS EXACTLY WHAT MANN BOILS DOWN TO. You take out that data and its over-weighting and the hockey stick disappears.

Followup on Mann's use/misuse of bristlecone pine records ... here's a source that indicates what the records look like DIRECTLY ... consider if you think this supports a "hockey stick" record:

From Determining the climate record, Prof Mandia of SCCC:

"LaMarche (1974), Lamb (1995), and Baillie (1982) have cited various tree-ring data that indicate warmer temperatures during the MWP and cooler temperatures during the LIA. Fig. 4 shows tree-ring widths of bristle cone pines in California during the end of the MWP and through the LIA that suggest warm and cool climates during the MWP and LIA, respectively."

Figure 4: Tree-ring widths vs. time from California Bristle Cone Pine trees. (Source: Tkachuk, 1983)

Regretfully, I've not had time to pursue this as quickly and in as much detail as you. But if even the referees at Nature can't resolve the technical issues then one can safely say the case for global warming is too weak to justify restricting economic activity.

I see that McKitrick took down the actual reviewer comments (probably found them too damning). This is from another board where the topic of McKitrick's submission to Nature was being discussed and what the reviewers said! The follow are quotes from the reviewers. When you read them you see that not one recommended that it be published!

1) At this stage, I think any Correction or Retraction by MBH98 is premature and really not required.

2) The reply by MBH04 on the previous comment by MM04 addresses in. my opinion both points raised by MM04 in a convincing way. Although it is for a reviewer impossible to check all the technical details involved in this reply, they arguments used by MBH04 seem plausible, and I would say they are probably correct. This is of course no guarantee that the entirety of MBH98 work and conclusions are free of error.

3) In summary, judging from the present version of the manuscript and the response by MBH04, I now think that basis for MM04 has wavered and that further work , or further convincing evidence, would be needed to present a more solid case.

4) Considering the changes relative to the first version of MM04, it seems to me that the case presented by MM04 has weakened considerably.

5) Unfortunately, I have the impression that preconceived notions affect the potential "audit" by McIntyre and McKitrick. That would, of course, not mean that their assessment is necessarily wrong, but might explain the rather harsh and tricky wording used here and at other places by both parties, and I generally do not believe that this sort of an "audit" and rebuttal will lead to a better understanding of past climate variations.