Well, his complaints are a mix of correct and... weird I guess.
1. The amount of CNPCs in BG2 was indeed very large, so some of them were less developed than others - But I think I can honestly say none of them were boring and all of them added something to your group. Even Cernd, undoubtedly the biggest bore-fest in the game, had a pretty cool story with his son and all. I will again iterate my unpopular opinion that most of BG2's CNPCS easily triumph PS:T's in quality. But I really can't understand how BG2 could possibly have such an amount of quality content, so I can understand wanting less NPCs if that keeps their quality at BG2 level.
2. Saving Imoen was just last week a cause for a very long argument about the game with my flatmates - First, I will have to say the game actually doesn't make you save Imoen, It makes you either save her or go after Irenicus. If you hate her, you could just go after him for revenge or finding out what power he tried to untap in you. But both motivations are pretty weak IMO, so I guess I sort of agree (This is also problematic from the perspective of the game Damseling Imoen, thank you Anita for making me think of this). Though I will say they did a fantastic job at making you relate to Imoen at the beginning of the game, she had many dialogues with you, she's one of the only characters you could talk to about this crazy dungeon around you at this point in the game, and you can't really hate her when you understand that the subtext basically implies she was raped.
3. Eh. The dialogues in BG2 were the best. I'm not a fan of "dry" dialogues. I think BG2 got the mix of comedy, seriousness, flamboyance and dryness perfectly right and I hope PE can strike that same balance.
4. Athkatla was huge living hub filled with quality content wherever you sneeze, but it could be a bit overwhelming at first... Especially considering the quality of every quest sometimes made them incredibly long, which meant you were swamped with endless stuff all the time. I think the pacing in Athakatla could have been improved a bit to be less overwhelming at first.