im an achievement whore in a sense, not that you could tell by my completion rate (but I blame that on having 2 jobs, a kid, and Ive only had my 360 for like 5 months and went and bought like 60 games within a month so I have too many to choose from or pour 50 hours into) but I also think its a little crazy to totally not get the game based on achievements.
Hell gamestop, where I assume a vast majority of us are getting the game from, offers a 30 day guarantee on new games that if you dont like it you can take it back and get your money back. If the game is so short and the multiplayer sucks... take it back and by then Crysis 2 will be out.
Or better yet get gamefly. Dont miss out on what could be a great game. I heard a lot of bitching , albeit a lot less, when bulletstorms achievements first hit the site. Im glad I didnt pass on it solely for achievements because Ive played through the game 4 times now and enjoyed it every time.