Well, after reading Nick's review of Pet Sounds all I can say is that I'll reserve judgement until I hear it myself. It all comes down to perception and preference.
Obviously, Nick loves a center channel. While I think the center channel can bring a lot to the game, for the most part, I can quite happily live without it. A complaint about lack of center channel usage, for me, is a non-issue. At worst, it simply means there is no chance that the center channel has been badly implemented.
The other complaint I picked up on was that the surround mix is overly aggressive. When I read this in an a review, I have to smile. This usually means that it is a very discrete mix. Ah, this is what I like! This is what I was hoping for! Right on!
The complaint about it being "left-heavy" might just mean that they didn't compromise the discreteness of the tracks by trying to do some kind of front blend. Hey, that's cool by me!
The advice that you might be better off listening to the stereo tracks through a processor, such as DPLII, also reinforces my thinking that Nick prefers a "watered-down" ambient type mix. It's like the Guthrie vs. Parsons DSOTM argument. Is the emphasis on a front-weighted stereo image or a fully discrete, distributed surround image? I prefer the former. Those that prefer the latter probably are better off with a processed version of the stereo tracks. That's a great option and hopefully will keep those folks happy. The rest of us that prefer real, discrete surround sound will (hopefully) be happy with the surround tracks included on the disc.
Finally, I have to ask questions about the so-called low-fidelity, thin-sounding mono mix. I'm assuming that the mono mix comes solely from the center channel. If you've got a compromised center channel, then no doubt the mix is going to sound thin. Even with a full range center channel, it's going to sound markedly different than if it were "dual-mono" coming from the front left/right speakers (my prefered method for listening to mono). Nick doesn't supply us with enough info here. Again, I'll reserve judgement until I've heard it myself.
In any event, reading between the lines and putting Nick's comments in the proper context/perspective, I can say that I am even more excited about this release than I was before! To me, it sounds like they've made all the right choices. I hope we will see/hear more discs like this in the future!