I listened to the album earlier today after a year and a half or so of not listening it at all and these are my thoughts:
1) The drum mix is so bad. I mean, I know this is a recurrent theme, but holy crap they sound SO much better in The Astonishing. They're not still at the good-Portnoy sounding level, but come on. There were times in which I could only focus on the snare, and that sucks because it didn't let me enjoy the rest of the things happening in the song.
2) Illumination Theory is probably the best song they've done in their post Portnoy years, and thank the heavens for the Breaking the Fourth Wall version (just because of the better mix). The ending is so amazing and epic, but the album version sounds flat as hell. I can only hear the overpowering snare, Petrucci's low 7-string chords and JLB's chorus modified vocals. Where are my amazing Jordan keyboard sounds? I know he did some massive keyboard layering in that part, and it's practically non-existent in the mix. It sounds kind of artificial in a way, which is something that thankfully was corrected in BTFW.
3) The Bigger Picture is incredible, but once again it suffers of a bad mix. What could've been a top 20 song in my book ended up not cracking that list because of the overpowering guitars and drums. You could really hear the effect of the massive compression at the beginning, and that's not something I enjoy a lot.
4) Surrender to Reason is very underrated. The melodies in the chorus are great, and the middle part is quite enjoyable. Lots of people accuse DT12 of being a flat, generic and boring album; but songs like Surrender to Reason really stand out for being different in my book (and, for what it's worth, I think it's one of the better-mixed songs in the record).
5) False Awakening Suite would've sounded much more epic and incredible with the live orchestra/choir treatment The Astonishing had. Also, it's weird hearing the chocolate cake guitars at full steam all the time with some of Jordan's keyboards buried when they're supposed to be the most important elements in the song.
6) Someone just posted in another thread that Dream Theater is a fitting title for this album because it's kind of flat in its purpose, and I agree wholeheartedly. With a better mix, it would've been a nice collection of songs that should've been nice as introduction for new fans; but if someone asked to me to introduce them to Dream Theater I would beg them to stay away from DT12 until they've already checked out everything else. Kind of ironic, isn't it?
Throw away your comments, good folk.