The book I co authored says to play 6. Qb3 but Now I think 6. cxd4 is best [but equal] In practical terms if you do not play pfren it is equal but chances for both sides. If you are playing computer assisted chess it is very equal.
Worstiest, are you playing against PP?
pfren, i also like this line(i'm currently playing a VC with this line as black, though my team made a mistake and it's in worse position now). The game continued 6.cxd4 d6 7.Bb5 Be7 8.Nc3 Be6, and the game looks equal.