I finished it today and it was a lot of fun, for sure. Megaman 3 is almost what you'd expected of a sequel of Megaman 2 (my favourite of the franchise and I didn't even write a review for it cause would be just ovation). Also, the final battles were enjoyable and the conclusion with the Dr. Willy battle was truly surprising (spoiler: my mind exploded!!!)
Anyway, I'll start saying the best points for me, and later I'll say the negative/bad points.
First, the sliding movement is a huge improvement to the gameplay. It adds dynamism and fun to every battle. The inclusion of Rush is also a great touch, even though I mainly used the Jet and Jump Dog forms.
The robomans have more cool designs and they have a variety of combat. Protoman is a nice surprise, but fighting with him is kinda boring since he have few movements (also, when I fought the misteryous crash man the game just crashed. Was this one of his powers too?)
The music sure is good; my favorites are the top and spark man theme, willy fortress 2 and the (goat) proto man theme. But, c'mon, megaman OST isn't just good, IT'S ONE OF THE BEST AMONG 8-BITS GAMES SONGS! Megaman 3 didn't have any standout songs for me, and perhaps my expectations were too big due to the amazing music in Megaman 2.
The aliens and other planets in the plot is interesting, but the story is almost pointless since it doesn't feel that the game is even telling one. The lack of a intro don't helps too.
Now, let's discuss what I didn't like: rush marine form is almost useless. I don't recall using it for the most part of the gameplay. Jet form was my go-to for most parts since it makes the stages a piece of cake. But my BIGGEST disappointment with megaman 3 lies in the weapons, like, I really don't think hard knuckle and gemini laser have other good use than defeating the bosses. Others like the top and snakes are difficult to use, and the rest are just plain boring. I really hope megaman 3 is the only game in the series with lackluster weapons.
In conclusion, megaman III introduces some cool mechanics, with some fails though. I'm not a big fan of the "megaman" formula, so my experience with this game is similar to the others: megaman is a fun game to play for hours, get frustraded, play more hours until you beat the whole thing. Get it?