Of course it's a yes.
Some still can't believe that Jim Carrey can indeed perform without resorting to his popular over-acting, and to those faces that have driven so many people insane with killer instinct (me included) in the past. For those as secure in this knowledge as to missing out on true wonders such as The Truman show or Eternal sunshine of the spotless mind (script that could never be praised loud enough), using Yes man as therapy for coming back to Carrey's worthy films is a must. Being fair, Yes man is somewhere in the middle (low middle, maybe) between the actor's histrionics and the two modern classics above, but hey, it's a first.
Yes man is a scream to life. For life. Quite a few hilarious moments and memorable comic scenes and characters in this very entertaining feel-good film (yeah, “feel good”, never understood what is wrong with that) may only make you feel better about this complicated but enjoyable adventure of life.
ALSO, Zooey Deschanel (The Hitchhiker's Guide to the Galaxy) is in it. If there is a cuter, more loveable creature in God's Earth, producers have not taken notice yet, or she would be in the film instead. Producers are not idiots.