This is the Comic Blade Drama CD series version, so the casting is different from that of the TV-series. Akari is voiced by Mizuhashi Kaori (Pepper in Chiccha na Yukitsukai Sugar), Alicia is voiced by Inoue Kikuko, and Aika is voiced by Hayashibara Megumi.
First, Inoue Kikuko playing Alicia was an interesting surprise for me because when I first read the manga, I thought she could be considered for the role instead of Oohara Sayaka. However, Alicia is actually bit of a teaser, and it's actually not all that subtle, either. Because of that, Oohara Sayaka would be far better fit for the role than Inoue Kikuko. Already, TV-series casting is one up from the Comic Blade Drama CD casting.
Now, Hayashibara Megumi!? I haven't been following her much lately, maybe because, well, there really isn't much to follow. It sure was interesting to find out that she's still playing roles. You really can't argue with her status. Aika isn't particularly extraordinary, so I don't have an opinion about which casting makes more sense, though, MEGUMI or Saitou Chiwa.
I don't know Hazuki Erino (Akari in TV-series), so no comments there, either.
Story wise, this CD covers the first two manga volumes, with some mixing and matching, plus one special. It covers quite a bit of the book, but it didn't feel rushed at all. If anything, it felt boring sometimes. I think that says something about the pace of the manga, at least the earlier chapters of it. I don't think the script is all that well written, either.
Basically, I don't believe these are required purchases, even for ARIA fans. But that's what I think, and so it doesn't have to mean anything to other people.
