I love this movie, and comedy duo - Simon Pegg and Nick Frost. And who doesn't adore Jason Bateman?
I think this is well written and hilarious. The CGI is fantastic. Paul is so cute - you cannot help liking him. It is refreshing to see a nice view of an alien.
My only critic comes from my stand as a person of faith. The denial of a Creator is going to rub religiously sensitive people the wrong way, especially with the length it goes with Kristin Wiig and John Carroll Lynch's characters. If you can overlook that, you will find this a very entertaining movie. I, personally, don't think alien life negates God - just changes interpretations of religions - so I have enjoyed this film multiple times. Besides, we all have a right to our own beliefs.
It's a comedy meant to make you laugh. It does that and does it well!