I have heard of decent rattle can paint jobs, but have never seen one myself. Every one that I have seen looked pretty bad up close. Save your time and money and opt for powder coat as Mr IGH recommends.
Having said that, I can also say that everybody should enjoy painting a bike at least once. I just finished clear coating a frame that I have been working on. I have a decent HVLP gun and enough experience to understand the variables (thinner type and amount, spray pressure and pattern, paint flow, etc.) as well as having painted a dozen or so bikes. Even so, I have never been able to do a perfect job. There are so many surfaces to hit that you are bound to get a bit of roughness on non-target surfaces due to over spray. Depending on the paint, this can usually be rubbed out, but that takes time and effort.
Good luck.