Pre-Ordered, bought and played Gears 1. Absolutely hated it. It was pretty much impossible to get a kill with the rifle due to a combination of teammate revives, refilling health, and overly agile characters. The best weapon in the game was the shotgun, so the entire game turned into a bunch of buff dudes rolling around cover and firing shotguns at each other point blank. The host always had a huge advantage too.
Single player was a short, pointless campaign, with terrible characters.
I hear the 2nd and 3rd games were legit good though.