And another thing: after 1. Bxh7, KxB; 2. Ng5+, BxN, 3. h4xB+ (discovered check)—the main sequence considered in the previous paragraph—Black doesn’t have to play 3. …Kg8; he can instead reply by bringing his king out to g6, resulting in the position to the left. White mates in three moves, starting with 4. Qh5+, Kf5 (forced). Then 5. Qh3+, and now if Black plays his king to e4 White has Qf3#; if Black plays his king to g6 White has Qh7#.
These sequences are worth a good look. They aren’t obvious, and tracing them through will give you a further feel for the types of possibilities that can arise in this attacking pattern. Once the king is out in front of its pawns it very quickly can find itself in deep waters: White’s pawns may greatly limit its mobility, and if White’s queen can move around with protection (as it gets here from the rook on h1), look out.