It's clunky and really designed for stuff like DnD type games first. That said, after about 200 hours across various games and reading the documentations every few months, I finding Roll20 to be pretty good overall. It does everything to some extent, even if it doesn't do it all well. (especially cards! Gah the card features are so limited!) I'd really love a better alternative, but am glad at least something like it exists.
As for alternatives? I know some folks actually use Tabletop Simulator.