My main gripe personally was how really unbalanced the character focus was in the anime. I felt that Yayoi, Yukiho, and Hibiki got too little focus while Miki got too much focus. I like Chihaya but I felt that she got way too much focus as well in the second half of anim@s. Hell, Miki and Chihaya both got more focus than Haruka which surprised me considering Haruka is supposed to be the "Main Heroine" in im@s.
The anime is so difficult for me. I was happy for its creation and it basically did what I intended and expected for it to do: represent the game franchise and overall culture of the iDOLM@STER in a way that is true to the series.
Ditto, to a point. Some episodes were hits, and some were misses - I'll probably get into that when I go through my list of favourite characters - at least, their anime performances I suppose. Hits, I'd argue 13, 20, and 24 were good, and as Misses - ... well, 25's the biggest miss of all.
And the characters in the episodes - I wonder if anyone has a statistic of how many times Miki hijacked everything. Sometimes it was fine - when she acted serious - Episode 8 and 13 come to mind (You'll have to do two intensive dance songs - So what, I'll try.) - but when it got selfish and annoying - Episodes ... too many to list ... you get the picture.
That last concert was ridiculously underwhelming. It was so underwhelming, I actually really disliked the song and outfit until I came back some time later and watched it again. I then realized they both weren't that bad. Even with that said, I don't think that song was very "final concert of last episode" worthy.
Same thing with the ending theme for the last ep. I think it was called Issho. Very boring choice for the last episode. I'm not saying make it hard core epic, but a song like Massugu or i would have been a better choice (though those two songs were already used).
I kind of wish there was more interaction between characters that don't usually interact. I'm not harsh on the show in this regard, though, since there's only so much they can do since they packed a lot of events in the show.
Says all you really need to know about Ep 25. The concert seemed a bit weird, the Ready/Change combo was really awkward, ... and in closing ... Massugu would have made a brilliant ending song. i, which they used to end Episode 13 would have also been acceptable.
Where the hell did they pull Issho from?
about the ending: afaik there will be a 26th episode on the disc release of the series. maybe we'll get something better there
A 26th episode? Say what?

My beef with the anime is that Haruka kidnapped a kid and got away with it. Some role model. 
I'm confused as to if the kid was even there. I mean, it was a kid, who somehow morphed into a mini Haruka, who then morphed into Haruka of Episode 13, who then ... disappeared?
I think Haruka should lay off the sweets for a bit, right? XD
Eep - probably too long. Just wanted to get back into this convo type thing