An argument against the Petroff is it leaves very few imbalances, which are what leads to winning chances. The imbalances may be later rather than never especially in amateur play so under master level there seems to be nothing wrong with it, and even at GM level Kramnik defeated Leko with a Petroff before in a famous two rooks vs. queen ending (even in Super-GM practice imbalances show later in the Petroff) and the pawns were on the same side of the board too!
I know enough Four Knights theory (both the 1.e4,e5 2.Nf3,Nf6 3.Nc3,Nc6 4.Bb5,Bb4 5.0-0,0-0 6.d3,d6 7.Bg5,Bxc3 8.bxc3,Qe7 9.Re1,Nd8 10.d4,Ne6 11.Bc1 lines and 7...Ne7!? lines.) to not worry about The Four Knights, another good system where imbalances are delayed and there's good scope for creative play and strategic thinking for either side.
If white wants to win, he can try 1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. Nc3 Nxc3 6. dxc3. This variation is quite unpleasant for black if they want a drawish game. By the way, this is the reason why I stopped playing the Petrov