I would not say that this series is on a par with Flashman, and it's not quite on a par with Sharpe either. Hardly anybody can equal the humor of George MacDonald Fraser, and there is quite a bit more psychological drama in the works of Bernard Cornwell. However, it's quite a bit better than the works of Edgar Rice Burroughs and H.P. Lovecraft. It's more of a modern style thriller, with a fair amount of humor thrown in.
As with so much modern fiction, the action is pretty fast paced, as if the writers are all writing for the movie script rather than writing for literary quality. But it's pretty fun stuff. I'm planning to get the other three books and read them. The lead character is pretty plucky and resourceful, and can definately fight, much like Sharpe. But he also has moments in which he is running, and is pretty scared, and he is not too honorable, much like Flashman. But he is probably more like Indiana Jones than either of those characters.