Just rolled my first character and got to level 23, so far I've noticed that being a siphoning Nightblade with a bow is utterly brilliant when it comes to DPS. The initial burst is outstanding! dropped some bosses down to 30% health before they even got a chance of coming near me. Is it just my rotation or are other people seeing the same amazing bursts of damage?
Stealth can be quite nice, but there are a number of quests where mobs are spawned aggressive to you, so you don't get the chance to use your sneak attack. That was the only downside I found when playing one.
In beta I was torn between Night blade and Dragon Knight.
The reason I chose DK was because I dont like how stealth works in ESO at the moment..its...very limited. You only have 1 opener and the stealth sight cone to me is too wide.
Oh ...and the DK skills are friggin awsome and I love the group utillities and synergies and versatillities in the builds far more than you can do with a Nightblade.
If you're in doubt about what to make ....have fun with a DK