It's not first, Anoncoin had i2p already in 2013.
It also has native Tor, so the user can choose between
the two.
The choice to limit the network to i2p only is from
the anonymity standpoint, a bad idea. i2p, although
in some respects more advanced than Tor, is just not
yet mature enough to support user privacy on the same
level as Tor does.
Actually, I believe div built native i2p for bitcoin in 2013 and anoncoin implemented his code after that.
It even says copyright div in the sourcecode. Cravedev didn't even change the default tunnel name.