Not much to say about it that hasn't already been said about the TV series. The animation quality is slightly better, and the stories seem slightly more elaborate. More budget to spend on backgrounds, I guess.
I felt a bit sorry for Miu, though -- she is constantly looking for validation from Nobue, but her way of doing it is so obnoxious that she makes herself impossible. And then she pulls a prank that makes everyone laugh, and all the tension leaves the group. That's a weird dynamic they have going on.
If you didn't like the TV series, the OVA isn't going to win you over. But if you liked the TV series, you will find the OVA to provide three great episodes. I'll give it a 7, just like I did with the TV series.