Is he worth signing?
He's somewhat inconsistent, prone to nerves, and not really a top of the line player. He'll be a perfect fit at Arsenal.
In seriousness... decent player on his day, has the right (Ferguson) attitude which you probably need more of. He's from the group of Ferguson players that always showed promise but never quite reached the super heights of others - but Fergy always made them look good. I don't think he'll let you down, just be clear you're getting a very good squad player and nothing more.
The fact Evans doesn't make the England team probably says it all.