I'm using a clone/phantasm build for my Mesmer. It's really the bomb. It might not be the best DPS but who cares. It's fun. I keep flipping between a build focused on Staff and Scepter/Pistol and one that uses Sword/Focus and Scepter/Pistol. For the latter, I enjoy having a run buff that's on a short timer. It's extremely convenient for harvesting.
The Warden does excellent damage but the fact that she doesn't move is a bit of a pain. It also feels strange opting to be in melee range in cloth!?! Having started as a Guardian in heavy armor opting for melee range, doing the same in cloth feels odd. The Mesmer doesn't seem to take any more damage than when I'm using all ranged weapons but I'm having a hard time wrapping my mind around it in general.
Both builds are enjoyable and suit my prone to solo anything style. I can take on more mobs at once with the 1st build since I continue to damage regardless of distance from target. For the second build, I have to remember to kite to the stationary Warden which I often forget to do so she's only melting face on the 1st cast where she runs up to the target. I just can't make up my mind which build to trait for long term. I'll use both weapon sets for different situations but I want to trait for one of them specifically.
Non-shatter builds feel like when I multi-boxed in WOW. I use similar strategies of trying to place the clones around the mob so that they have to ping back-and-forth when aggro shifts. This forces them to spend time traveling to and from, if they're melee. It works for range opponents as well, though there's not as much delay. They're still forced to turn this way and that, to hit targets. For easy targets I just spread them out a little. The opponent dies too quickly to worry overly much. For myself, I circle strafe so that new clones continue to be spaced around the target.
It's good fun. I love the pistol's Magic Bullet that stuns/dazes/confuses multiple targests. I'm a bit of a pistol whore which leads me to want to trait into the first build I linked. Once I hit level 30, I ran around the other racial zones cherry-picking skill points to obtain my elite. Turning opponents into Moas is muhahaha goodness. But nothing beats having mass invisibility!!