How fast is the Time Capsule?

Anandtech has a recent review of the new TC. Go there and knock yourself out.

TL: DR version of the review is the drive isn't terribly fast, particularly on writes. On continuous large files it can reach 80ish MB/s reads and about 35 on writes, but for smaller files it drops a lot.

It's faster when connected via wired gigabit ethernet than over wifi though. Drives connected to the USB2 port are slower than the internal drive, at about 25MB/s best-case I seem to recall.

Mostly this thing is for backups, and not so much general storage, but you can use it for storage if your demands aren't too high.