I have one, and as mentioned, they are great if you're space constrained, and I find that the developer lasts an absurbly long time, maybe it depends on the particular developer you use. FWIW, I mostly use Moersch Neutral or Formulary Liquidol, both of which are long-lived formulas.
The only downside is if you need to do multiple batches of prints, it's hard to do more than a couple of large prints at a time, dishes or trays work better for that. But that's a minor issue.
On Roger Hick's website he shows how he has mounted a Nova into his darkroom counter so that the top of the processor is flush with the counter surface, allowing space for trays if the Nova won't be used. It's something I intend to do with mine during my next DR remodel.