I believe you can still get Bob's Dream on your computer for free. I remember it used to be available to download at www.apple.com/downloads. Bob's Dream is fun... a nice platformer, but the most I'd pay for it is $1. I'd definitely go with Rolando. It's a much higher quality game than Bob's Dream.
Bob's Dream doesn't look as nice as Rolando and the controls are worse (not a fan of onscreen buttons, though their implementation isn't too bad in this case). Also, the sound effects in Bob's Dream are bloody annoying whereas Rolando's are nice and unobtrusive.