Spikeout is not only the rare early 3D beat em up that actually feels good to control, but it also has a very innovative combo system where you can build up a combo with different moves instead of relying in two predetermined kick and punch combo strings. The game also shows off Sega's technical mastery over the model 3 hardware, being a really good looking game with support for up to 4 players in connected cabinets.
I do think it's way too fucking long though, no arcade beat em up should be over an hour and a half long.