A decent film with some ok laughs. Those that loved the vastly overrated The Hangover will probably like this. Those that prefer character driven comedy like I Love You, Man will probably be bored by a lot of this.
Relies too much on (FAR too obvious) pop culture references for the majority of its jokes, the characters are unlikeable jerks (except Craig Robinson), and the overall message is very shallow...better example of an 80's retro film would be The Wedding Singer...better example of a time travel comedy would be Bill & Ted's Excellent Adventure.
Best part of the film is easily Crispin Glover, and his role is quite small.