It is amazing, but it has the issue of not having that many user. I2P is great, but because not many people know about it and that it is harder to set-up than going to a torrent site and downloading, not many people use. I2P speed improve the more people use it. One other flow I found is that I2PSnark is awful and there is a need for a better client for it. From my understanding the more you seed, the better speeds you will get, thus it encourages seeding which solves the issue with normal torrent were a lot of people will not seed after a while. I think it is a great idea specially now that many torrent sites are being taken down.
The problem is that qbitorrent doesn't support DHT via I2P only trackers, you can clearly see the difference in peer numbers if you use I2PSnark. Officially it should work, but I couldn't get any peers.
Officially it should work, but I couldn’t get any peers.
Officially it won't work. It's impossible for qBittorrent to support DHT via I2P when Libtorrent itself does not support it. qBittorrent along with many other torrent clients are based on Libtorrent.
qBittorrent works well enough as long as you're adding I2P trackers to public torrents you want to find I2P peers with. It's not great but for now that may be the best solution aside from using I2PSnark (which like you said isn't that great).