I have one on my new nano. It's plumbed in and running but there's no media in it. I put some in at first just to play with it.
It's a solid piece of hardware but I can't really give any long term feedback. Honestly, I'm not sure if I'll even end up using it on this tank unless I can't control nutrients otherwise. If I don't use it for biopellets, I may wrap it in one of those flexible LED strips and grow Chaeto in it.