Melee multi at least is quite interesting. One of my 3v3 placements was just sad; the enemy team (PPZ) successfully rushed me and destroyed my nexus and some of my pylons, but not my probes. One of my teammates (we were PPT) was simultaneously being attacked constantly with zerglings, soon by void rays and stalkers. My third teammate was holding out and helping both of us with his bio ball of death, though.
After I got the enemy out of my base, I received enough minerals from my allies to rebuild my nexus and make a single pylon. That pylon, incidentally, powered up all of my intact buildings, including a forge, cybernetics core, and 3 early-game warp gates. I received more money so I could pump out stalkers and survive against further attacks. All the while, the teammate being hit by zerglings and stalkers is spamming "We're ****ed." While I'm wondering how we haven't managed to lose yet (these opponents appeared to be good, considering their effective early rush). I eventually get 7 warp gates and some ground upgrades, then push out to my enemy-occupied natural expansion, and take it. At the same time, void rays are raping my protoss ally hard, so i send my large mob of stalkers out to help him. Eventually, his base is rage-stomped by a built up force of zerg and protoss and we're left with me (now recovered fully from the rush) and my terran ally with his M3 bio ball of death. At some point I build up 57 stalkers and send them against the enemy high-yield expansion, but I get hit hard with a coordinated roach, void ray, and hydralisk strike. However, I softened the enemy well enough that the M3 bio ball was able to mop the floor with the whole 3-player enemy force. I took that rich mineral expo, built up a crapload of stalkers as our enemies stupidly pumped out void rays and carriers (they should have gone with mutalisks for my stalkers and a force of zealots, colossi, and a handful of phoenixes to handle the Marine-Marauder-Medivac force. We attacked them on two sides, raped all of their expos, and then proceeded to systematically wipe out all of their bases.
This was mainly done 2 vs 3 throughout the whole game, as I was punched out early in the game but made a recovery. By the time I was back in full force, one of my allies up and died, so we were always undermanned. I still don't know why the enemy managed to lose despite all that. Maybe M3 is really just that good. Also, I somehow managed to get the highest score at the end, to my surprise.
In previous games, my protoss ally always cheesed the game with a surprisingly effective cannon rush. One time, he actually managed to create a wall of cannons, pylons, and warp gates about 12 tiles deep.
Also, it's always nice to get the 5-win-streak achievement on your first five games (not counting the beta).