I think the 303 is mint to start out with as an all in one box. There are some issues concerning the midi that may or may not affect you depending on what you want to do outside of it. But honestly, as an all in one solution it was ****ing awesome. I really learned alot about creativity because once you mastered the box, there was, for me anyways, incredible simplicity between having an idea in my head and writing it out on the MC 303. You don't have to solve any problems if you just keep your music inside the box (and really, there is no reason you have to go outside). So, maybe its not pro hardware, but it can be uber-inspiring. Lets you quickly get on into the exploration of sound and sequencing.

I agree Yamaha samplers might be excellent samplers for the price they go for these days, but they, too, have their problems; so best know before hand what you're getting into if you go that route.