I don't follow Marvel comics... or I didn't till recently. I do collect Incredible Ironman, but that's it. Cause of that I only know of Deadpool from cross overs, but I collected the Agent X mini series (I was a big Udon fan back in the days) which is a spin off of Deadpool and really enjoyed it, so I knew the type of humour I was expecting in the movie. Also, a lot of my friends do read Deadpool, so I hear a lot about what his comics are like. Based on a description of how the comics work like at their best, the movie hit it on the nose.
I'm a huge fan of B grade movies, and dorky humour so I loved it :) I don't have a comparison to comic first hand though. I feel though that you should be able to appreciate it without the comics to back it up though. I had a lot of fun watching the movie, and I loved the lets plays of the game. He's.... not a serious character, and you need to keep that in mind when you follow him. if you don't like blood, or crude talk, he's no good. I find him fun to watch in small doses. I wouldn't want to read a comic about him though.