So the mesmerist class looks pretty simple, in terms of how it works and what optimal ways to build it are. It works EXTREMELY well with rogue, since you can pick up Improve Feint without needing Combat Expertise, so I'm sure there will be plenty of multi-classing there.
For pure mesmerists though, it looks like you'll have many of the same builds as a bard. Prioritizing Charisma, Con, and Dex are always going to be good for you, so its just a matter of deciding how much melee/ranged combat you'll be doing. Doesn't look like the class gives you many ranged options, but an elf or half-elf could start out with a longbow from level 1.
I dunno, I'm just spit-balling as I fall asleep. What do you think? I kinda want to make a NG mesmerist who works with the mentally insane to help understand and heal their fractured minds.