If you run both Tor and I2P at the same time, it's harder to do eclipse attacks against you.

Also, addnode= with your friends or other parties you trust, can be useful.

Browsing is way faster than tor and I encounter less captchas.

You just need to run your node for some time at the beginning for discovery reasons.

But I only use I2P to visit one specific eepsite. So don't know how the rest of the network behaves.