The path to the sphinx is great! I guessed the riddle on the third try... The boots of levitation are a worthwhile reward.
By the way... I found a bug (I think).
In the center of the map, near the second Haven castle, but slightly to the right (the rightmost part of the island), there is a group of monsters (unicorns and others), but you can't attack them. The cursor turns red, but the hero doesn't move to attack.