It all depends on the bike, it's current state of finish, your budget, its intended use, and your care factor (will you care what others think). You will have a lot of opinions and reasons in yes, no, and maybe flavours. I've seen some great powdercoating examples on this site. It is tougher and cheaper than a wet paint. It is much harder to remove PC. Although I did use some spray on gasket stripper to remove powdercoat from a crankset & it worked very well. If you do decide to PC, do your homework or go with a recommendation, with both the sandblaster and the PCer. Use people that are familiar with bikes and have a good rep.

Tell us a bit more about the bike etc?