Mesmer alt
The pro is versatility. There’s pretty much a build for everything. The con is the learning curve. Leveling will be hard until you really start to understand how the powers and abilities work, both offensively and defensively. Others will tell you that we don’t have great condition removal but a few days ago someone pointed out that there’s even a build for that.
Leveling is also slow. Mesmer is one of the hardest classes to level in the early-middle levels (10-50) because enemies are stronger but you don’t quite have the skill points yet to fully trait into either burst (typically shatters w/ GS) or condition (staff w/ additional bounces and lots of clones). However, there’s a ton of different builds. It’s very daunting at first, but just go into the Mists and fiddle with your traits. You’ll eventually find something that fits your playstyle.
I agree with Crossplay on the versatility Pro. I’ve rebuilt my mesmer a bunch of times just for fun (on my second set of gear, and at least 4th set of traits at level 80). It can definitely stay interesting for a long time because you can play different roles with very different styles.
The cons are with respect to low durability at lower levels and the learning curve. If you play a class that generally has high durability like Warrior, Ranger, or Guardian, you’ll find that some encounters will be out of reach for solo play for a bit longer. At low levels, you’ll find that the only way to survive solo is to kill the threat quickly because the Mesmer self heal without traits is very weak.
I strongly recommend unlocking Metaphysical Rejuvenation ASAP as it makes playing at the lower levels more forgiving.
Pros : great damage, survivability, versatility, utility, range builds, melee builds, and very fun.
Cons : slow leveling, swiftness/mobility