Ninja Gaiden is pretty tough.. at least for me who is new and not that good at fighting games. It was fun, but frustrating.
I havn't played Burnout Revenge yet, but from what I heard some people like Burnout 3 : Takedown better. I really like Burnout 3, and you may be able to get it on the cheap right now. I heard that in Revenge you can basically ram cars straight off the road in a completely unrealistic fashion.