The opening shown here is quite common. Is it generally a good or a bad idea to give up a kKnight and a bishop for the castled Rook and the f-pawn? In terms of their "standard" value, both pairs are generally considered as being worth 6 points.
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
1.e4 e5 2.Nf3 Nf6 3.Bc4 Bc5 4.Ng5 O-O 5.Nxf7 Rxf7 6.Bxf7+ Kxf7
Black can just move back to f7 and slide his rook over on completing development, and that's still using fewer moves than White did with his KB and knight.
– aschultz Sep 24 '16 at 00:38