Black doesnt seem that toasted after 5.Ng5 f4; there is a game on this database where black wins this game.  

not a good opening

  It would be hard to resist 5...Nxe;6.NxN,d4 and with the queen check at h5, there's stuff to play with.

Black is toasted after  5. Ng5. If Nh6 Qh5+. Don't try this

After exf5 d5, black seems fine.

not good for black.