...the majority of my review can be summed up in 6 words: "It's called Hot Tub Time Machine." It's a stupid movie, but it knows it and revels in it.
There are a few flaws in it... It wasn't as consistently funny as, say, The Hangover; most of it's laughs were 80's nostalgia based, but they didn't go as far with it as I thought they would. A staple of the 80's comedy was the competition, like a boat race or a eating contest, that they would have to win to save their friend's grandmother's house. Since John Cusak was in it and was an integral part of that era, you would think that he would have put a little more thought into it. Also, the time travel would have created a paradox that the film makers kind of overlooked which probably would have ended the world.
Hot Tub Time Machine is funny, raunchy, stupid fun. It's definitely the kind of movie that you should get high before going to see.