Wait for Streets 2, if you can!
HOWEVER, that said, the first Streets of Rage is not a fantastic game. I consider Streets of Rage 1 to be practice for Streets 2, where the combat is deeper, the graphics better and you don't have Police cars containing bazooka-toting officers driving onto a moving boat! I see Streets 2 is TBA 2007, so if you can't wait, splash out on number 1 (it was raining, so I did and, hey, 2 hours entertainment - not bad.) Otherwise my advice to anyone who wants a really good beat 'em up is to wait for Streets of Rage 2.