http://ysshlyesehcnscptskrpai4iupxccuvfcpbxk37kclbs3rsaqmolzaid.onion/darknets.html
The java versions are user-friendly, while i2pd is more for servers and fat kilopound hackers living in smelly basements. The I2P darknet is a closed garden network, it's like a secret island, meaning you connect to it but not out from it. It has really bad clearnet reachability in comparison with Tor, like it has only one or two exit nodes and they are disabled by default.