If you're a nobhead who automatically goes into bash mode when you hear the word "fan game", please go read some other thread.
I used to be into fan games, and after finding Sonic Robo Blast on my HD, I recalled this one, and tried to find it. I'm glad I did. Compared to modern klik standards, it's pretty bad, though it has a kind of "vintage klik game" charm.
The graphics are mostly original, though looking rather flat, with some library graphics thrown in. Sonic and all enemies are much smaller compared to SRB, which works to the game's advantage, as there's no scrolling (just like SRB). The author has done a good job on the level designs considering the lack of scrolling (try making a non-scrolling platformer yourself!) Music and SFX is the standard fan game fare. Unlike SRB, there are no "unfair hits" (when you lose your rings even though you're jumping on an enemy). Sometimes the animations of bosses freeze when you hit them, but you can still defeat them in that state.