(Rating is 4.5; no half star option though.)
I have come back to this with Beta 30 and I stand by what I said back in August. This is on par with Streets of Rage 4 as a package. In some ways, it actually outdoes that game. The mechanics connect well and are polished to a sheen!
...Except for a few parts. The 3-Star Super Attack is the main issue I have. For one, it's hitbox feels too small. At least with Axel, it LOOKS like it hits enemies in a circle, but it doesn't. The second issue is that, if I've grabbed an enemy, I can't use said attack. Paired with the hitbox issue and the foes moving around, it has always felt too janky and unreliable to use consistently.
One thing I personally would like to see is a Composite Video filter. The heavy amounts of dithering on the original hardware was because of the 61 simultaneous colour palette out of a max of 512 possible colours. So Composite Video blended a dithered picture to either make more colours or allow transparency, which the Genesis is not natively capable of.