Pros of being a mesmer: its fun
Cons: getting into a group can, at times, be hard.
Yes, mesmers can solo, and a great variety of creatures at that, solo builds range from pure mesmer to mesmer + secondary profs. depending on what you're soloing at the time.
Rangers can interupt more skills atm (I am soo hoping for more skill interupts for mesmers in the next chapter) however, a mesmer can do nasty things like powerblock a spell

and no ranger can compete with that.
Me/N is a wonderful combination, curses provides some nice skills, with my personal favourite being parasitic bond (degen + health for me when it ends).