Here's my opinions on some.
I'll start from II.
II: Having an arcade and the console version makes you think twice. A lot of people claim that the voice acting was bad, I'm neutral about it. Since the arcade has a more complex sound system, the sound is clearer unlike the console version. Anyway, I love SCII design wise. It was a step ahead of any other of that time and is still ahead of some games today.
III: My absolute favorite SC, no matter how broken it is and how Setsuka knows what move you're going to make a second before you do. The graphics were very unique and pleasing, this took a lot of negaive criticism as well. From the content, the new characters introduced, music, and including all of the past characters as guest, made me give it an A+.
IV: This game wasn't exactly on par with it's predecessors, but still had unique features such as a new graphics engine, online play, and a design overhaul. If the game gave what tourney players wanted and had a revamped single player experience, it would have been on par with 3... almost.
V: Here's where it gets messy. This game is a controversy between players in the community. Booted characters, new fighting system, story, and other minor things cause huge fights in hate/love threads dedicated to this game.
I think the game is iight, I'm glad they gave us another SC.
That's all I got for now.