Reading this thread, I am having a sudden surge of nostalgia.
I've gotta buy a new cooling pad and take another run through ME1 - maybe as an Vanguard this time, or an Engineer.
Yeah, the combat was kind of shit, but it had one major advantage over ME2/3 - free-roaming on planets.
One of my favorite things to do was find some enemies on a planet, then get out of the Mako (because it sucked) and fight on foot. My sniper could hide behind scenery and take out enemies from afar - I loved fighting Geth Colossus that way, because I my cool-down took just as long as it did to strafe behind cover, wait for the Colossus to blast said cover, and then step back out and put another bullet in it's face. If I screwed up, it was usually an instant kill (or close to it) but that's what made it exciting.
The battles where I was actually supposed to be on foot, like inside bunkers (it was always those rectangular bunkers) were usually pretty dull, but the outdoor battles made up for it.
One of the saddest things about ME2's Firewalker DLC is that you can't get out of the stupid Hammerhead and fight on foot. If they'd let you get out of that stupid thing, then the Firewalker DLC would have been insanely fun!
Oh, and another thing - I liked that you could ambush enemies in ME1. If you successfully snuck up on enemies and started sniping them, they wouldn't know what the fuck was happening and wouldn't get into cover (or they'd get into cover the wrong direction) making your ambush all the more awesome. In ME2/3, enemies (usually) just spawn in and instantly know your location (unless it's plot that they don't). The multiplayer is particularly guilty of this, with enemies constantly and instantly knowing your location at all times.
Don't get me wrong, I loved ME3, but... I do miss certain aspects of ME1. A game that had ME3's combat, and ME1's free roaming would be the perfect combination.