As far as hitting he's a pretty good copy of Mueller:
Youkilis career: 271 AB, 8 HR, 44 RBI, .371 OBP, .417 SLG, 788 OPS
Mueller 2005: 339 AB, 5 HR, 44 RBI, .373 OBP, .410 SLG, 783 OPS
Mueller 2004: 399 AB, 12 HR, 57 RBI, .365 OBP, .446 SLG, .811 OPS
I'd still prefer Mueller right now. Plus, Youk has yet to prove that he can play every day in the big leagues. In time he will probably be fine.