At first, Assassins look to be a pretty strong class. High crit strike rates, fast attack speeds, double strike, and nice energy regen seems pretty promising. And it it looks as though you could take out a single target in PvP literally by pressing 1, 2, 3, 4.
However, the Assassin seems to me like one of the most easily countered classes in the game. I have seen very little self heals, condition removals, hex removals, etc. from the builds that people have submitted. All I'm saying is that I think the dagger combos are a bit overrated, and that it will take more strategy than most people think to play an effective assassin. Instead of assassin builds that focus on targeting a single enemy and killing it as fast as possible, I'm trying to think of some builds where you play like a _real_ Assassin, making use of the assassin's speed buff skills (which can be both offensive and defensive) and the unique shadow step ability. Example: tab between enemies until you find one that you can finish off, and teleport to an ally near that enemy. OR play a defensive assassin: watch your allies' health bars, when you see someones health start dropping, teleport to the ally and cripple/KD the assailant in order to save your mate.