When supreme commander 1 came out, i got it and thought it would be fun and great and... it wasn't, it was OK but it got real boring quite fast (it was fun the first few missions).
so because of that i was a little sceptical about weather number 2 would be any better so when i saw they had a demo for it on steam i downloaded and played it. First of all, it runs so much smoother then number one; secondly detailing is just so much better and environment has more in it, one thing i noticed about number one was that the maps were kind of sparse in what there was, its was either mountains, water or trees, and that's it; number two is far better in that regard.
Lastly it was just more fun to play, the second mission (in the demo) was pretty good; i won't spoil it but it was fun to play and the game overall flows better and it's easier to get to grips with.

all in all number two is actually an improvement on number one.

i was a total annihilation fan but i need a better comp to play the supreme commander 2 sadly. but i might be building a better computer soon with the tax money and all.