2...Qh4+!?(keene defence) is not an outrightly bad move. The idea is to play something like 3.g3 Qe7 where white has to adopt a rather unusual formation for the king gambit. Some authors have tryed to claim equality for black in this line, which is certainly playable, but i must say that by continuing quietly wth 4.d3 white usually gets a nice lead in development in an otherwise level position. So when you see 2...Qh4+ you shouldn't expect a quick win, but not an unpleasant game either. It's rather easy to play the position for white.
Thanks for pointing this out. I just read about 2...Qh4+ in the FCO, and yes, Black has a plan, to draw White's g-pawn forward with the paradoxical intention of taking on f4 only when that pawn is protected. Here is a sample continuation.
2...Qh4+!?(keene defence) is not an outrightly bad move. The idea is to play something like 3.g3 Qe7 where white has to adopt a rather unusual formation for the king gambit. Some authors have tryed to claim equality for black in this line, which is certainly playable, but i must say that by continuing quietly wth 4.d3 white usually gets a nice lead in development in an otherwise level position. So when you see 2...Qh4+ you shouldn't expect a quick win, but not an unpleasant game either. It's rather easy to play the position for white.