Some things I observed from the pugs last night and from looking around the map on my own time.
http://puu.sh/761Kk.jpg
The flat mid provides too much freedom of movement when deciding where to go for a team as a whole. This makes it harder for demos and soldiers to do consistent damage round to round. The flat mid coupled with medium-height objects allows for good scouts to rain hell down. The mid is incredibly scout-favoring.
http://puu.sh/761Lv.jpg
This sightline is pretty atrocious.
http://puu.sh/76219.jpg
Second is rather weird to hold because of all the intrusive geometry. The big thing sticking out of the spire gets in the way of a pretty nice forward hold for second. The giant sightline from main also gets in the way of that being a nice forward hold. Any forward hold is really destroyed by the fact that the other team has many nice places to spam you from.
http://puu.sh/762mn.jpg
This area into second really favors attackers, and is better off left unguarded by your flank because of the massive height disadvantage. This leaves your flank classes being pretty useless on the map, especially when tunnel is pretty useless for the other team to try to flank through.
Main is hilariously wide open to spam by everyone. Tunnel provides no positional advantage that main doesn't provide better, it's only useful for a coordinated sandwiching. The crates entrance is amazing for attackers, leaving the defending team's flank pretty much useless on the second point.
http://puu.sh/7631G.jpg
This spam position is too easy to get into. Defense also can't hold that side of the last effectively because of this, and because of the wall which denies them the ability to spam out attackers.
http://puu.sh/763E4.jpg
This sniper sightline combined with the spam position makes the left side of last for defense pretty ineffective to hold.
http://puu.sh/7639i.jpg
This area feels like a condensed gullywash river. Take that as you will.
Last seems to have the same problem as second, where flank classes are made ineffective beyond just trying to constantly attack the other team, but the attackers have such good advantages over them that this is overextending as soon as they leave the combo.
I don't know what else to change about last. It'd need higher skilled pugs to really stress-test it and find any weaknesses.