I agree that the OP is a little too euphoric and
I2P is a project in progress i.e., unfinished. However, that's no excuse for being so harsh
and ignoring the explanations:

http://www.i2p.net/home
http://www.i2p.net/how_tunnelrouting

However, I don't think that the common user of a filesharing network needs anonymity and I2P
will be much slower on average than the
usual way. Unfortunately, P2P has become a synonym for illegal filesharing.

Hell, if people gave a **** about security they
would use real operating systems, encrypt
their mails and wouldn't execute random files. Hey, you can have all of that for free and legally!
Who cares? I'll tell you: Nobody.