Looks great so far to my eyes, but I am aware of its division among fans. That's the problem when creating a retro gaming revival. Diehard fanboys expect everything to be pixel-perfect just the way they like it (in this case, 16-bit Sega Genesis art design), and will immediately pounce on you if anything is off. Personally, I don't mind the art style but I am aware that others may not like it.
As always, gameplay is the important thing. These videos demonstrate that the developers are following after SoR2 as their model, as opposed to Sor3/BK3, which introduced a number of gameplay moves to speed up the action. There is still the question of stage design and whether any set-pieces (such as battling the bulldozers or defusing bombs) will be included, or if any new elements will be introduced. And the cast of playable characters offers a good mix of old and new, but like many fans I am hoping that all the older SoR characters will be included, such as Skate, Max, Dr. Zan and the kangaroo.
My hopes are very high for SoR4 and I can't wait to see it released. It would be even better if this game was released on, say, Sega Dreamcast. I feel that a Sega console deserves a true Streets of Rage sequel, even if it's only a limited release. Heck, use that Maber pixel art and bring the title to Sega Genesis, especially now that that other indie beat-em-up appears to have vanished off the face of the Earth.