I was a great fan of Total Annihilation. I'm a fan of the RTS genre in general. I played SupCom online for a couple months but ultimately I have to confront the fact:
This game stinks. I desperately tried to enjoy it but I can't honestly suggest it to other people. I played for as long as I did hoping it would improve with patches, and while they fixed a lot of technical problems, the gameplay problems still persist.
The game *engine* is fantastic. It looks awesome. The battles are great. The units look fabulous and there are some fun and unique takes on some of the high tech units (the ones always featured in screenshots).
The problem is the gameplay is just horrid, both for online and offline play.
First of all, you should have dual core to play this game. They have done a lot of performance improvements since the game's release, but if you want big games on the big maps, you need dual core. Consequently, trying to do 3v3 games online is a nightmare as no manner how much you stress that everyone in the room needs dual core and they all say they do, invariably one player will not have it and the gameplay will bog down to intolerable levels. Online multiplayer gaming can frequently become unplayable unless you just stick to 1v1 on smallish maps.
The game has Vista problems (or Vista has problems with this game). It tends to crash on Vista during big games. So don't use Vista if you can avoid it. This is just another way big 3v3 matches end up failing -- if someone doesn't bog the game down with their slow computer, someone will crash out because they're using Vista.
The economy is unique and horrible. The economic model in the game is similar to Total Annihilation but with a couple of differences: map control quickly becomes almost completely meaningless and base defenses are vastly improved over what they were in TA. TA was largely a war of attrition against your enemy -- he builds 2 fusion plants, you kill 1. He builds 3 more, you kill 2 more. Due to the improved defenses of SupCom, that doesn't happen. By the time you can break through your opponent's defenses to destroy his fusion plant, you might as well skip the fusion plant and blow up his Commander instead, ending the battle.
So typical long games degenerate into both sides hunkering behind their defenses until one side can launch a single, fast, devastating attack that breaches the defenses and immediately ends the game. The long, continuous back and forth battles of TA are gone, I am sad to say.
On smaller maps, you won't get to that point, and you can have some good gameplay, but then you're not playing the game that was sold to you on the box and in the screenshots. You're doing low tech rushes on small maps and you're not going to reach the cool units proudly displayed to you in the magazine reviews.
All of this leads to a shrinking community, too. I made it as high as top 50 for my 1v1 ranking and it got to the point where I just couldn't find a ranked game to join. I sit there for literally 10 minutes "searching for game" and there's no match, because nobody near my rating is playing ranked games anymore. They all quit or they're all playing non-ranked games because ranked games on small maps honestly aren't that fun and don't represent the gameplay sold on the box. There are top players who have posted screenshots of themselves with 1 hour timers or more, waiting for a match.
This review makes me sad, because I loved TA and I wanted to love SupCom, but it's just not happening, and I don't think you're going to see any further sweeping changes to this game that will ever bring Ranked gameplay back into popularity. You can find people playing custom player-made modifications and maybe you can get some enjoyment out of that, but regular ranked gameplay is DOA and that's too bad.
Maybe the next game, Forged Alliance, will fix some of the problems, but I probably won't bother at this point. Between the way this game released and the company's reaction to gameplay suggestions on their official forums (bans), I don't see myself trying another GPG product until they can prove they've really turned things around.