The other guys pretty much covered it! The pro's are having a great looking gun (depending on the eye of the beholder, naturally). The con's are fingerprints and scratches. In my experience, fingerprints aren't much as much of an issue with a revolver as they are with a pistol. You've got to re-train your fingers a bit to keep them from molesting the polished surfaces, but, with a little practice, it becomes second nature to not get unnecessary prints all over a revolver. Racking slide and hitting the mag release are a different story, though.
Scratches aren't too much of a problem either, if you're careful. I bring one of those green felt mats to the range to set my polished 686 down on, rather than set it on the diamond plate they have there, and I use a soft cowhide holster (no kydex!) for concealed carry. If this is a BBQ gun that's going to get passed around and beat to hell, then either polishing is a bad idea or acceptance of "battle scars" on the pretty surface is mandatory. If a polished gun is treated with reasonable care, though, any scratches that it does get should be pretty minor and will buff out with the tried and true Mother's and a t-shirt process.