I got the DVD set of Season 1 for Susan, for Christmas. We watched through and finally caught up to current about a month ago. I love this show.
Agreed that it's not as edgy as the first season, but edginess is extremely hard to maintain. The characters remain strong. General observations:
Finn: Least interesting character, probably because the others all treat him like a star player, when he really the weakest musically of all the principles.
Puck: Sings the songs that I want to sing, consistently. Great subtle articulation of voice.
Artie: It's a shame he can't dance on the show. It must be murder to try to keep from tapping his feet.
Mercedes: I love her style of singing. Wish I could do it, but that level of extemporaneous improvisational harmony is mystifying to me.
Rachel: Basically Barbara Streisand in High School. Great voice, but I'd have a hard time choosing between her and Mercedes for vocal quality.
Britney: Like Anya on Buffy, she consistently has the best lines.
"What's your favorite song?" "My Hairband."
Kurt: My wife was so happy when he and Blaine kissed. He's gone trough more hell than any of the other characters, except maybe Quinn. Beautiful voice.
Santana: One of my least favorites, but I understand why you need a character like that. I could do without the lesbian subplot, which seems far more forced than Kurt's homosexuality.
Lauren: Meh. She's an interesting character, but like Finn, is there for reasons other than performance quality.
Mike: I'm glad they finally started expanding his character, but he does seem to lack any conflicts.
Tina: Also lacks conflicts. She was more interesting with (but not because of) Artie.
Quinn: She's basically a foil for Rachel, but surprisingly talented.
As for the adults
Shuster: Hard to believe he's still teaching school. The students can be talented without straining the suspension of disbelief: they're starting out. He ahs maintained his singing and dancing edge, but doing what? Teaching Spanish. His plot with Terry last year was nail-biting.
Sue: Outrageous character. I think every teacher secretly wants to be like Sue: says what she wants, does what she wants. She certainly suffers the consequences, but she always comes back.
Emma: I've grown to like her less and less. Back when no one believed in Will but her, the relationship worked. Now she just seems like damaged goods.
Overall impression: I want to live in Lima Ohio. Everyone can sing fantastic songs at the drop of a hat, with no rehearsal, and put on amazingly expensive shows seemingly without cost or preparation. That's one awesome AV club they have. And Piano Guy is like Lurch from the Addams Family. He's just there when you need him and disappears when your done.
The show is way over the top, but consistently enough that you just accept it as one of the ground rules for the setting.