As a Fitzgerald and Edge owner, I think its a great call.
College is not the NFL but Leinart played at the highest level of college ball and is a proven winner.
Talent wise I think Carson Palmer is a better QB but I think Leinart could turn out to be just a notch below his former mentor. He just does not have the character that Palmer has but he could develop that. By the end of next year he will be a top 5 QB.
With the weapons he has, all they need on offence is a decent O-Line and could be the NFC West Champs next year. It maybe a little early to make such predictions but all the pieces are their and they play in a weak division.