[Tarto]

I spent four nights at a capsule hotel in Akihabara about two years ago, just wanted to try for the sake of it.

I agree with the other replies, capsule hotels are surprisingly expensive for what they are (when I went there, the standard fee was 4000 yen per night). You'd better find a room at a cheap guesthouse, plus it'll be easier to store your luggage.

I wrote a small post about capsule hotels on my blog (in the accommodation category) check it out, there are a few pictures so you can see what it looks like.