I realize anecdotes don't really prove anything, but I ran my own little exercise...
I put a first-level Shade Vampire (yes, really, and without Durable, but not gimped otherwise) through two near-TPK encounters, along with a Vryloka Blackguard and a Revenant Gloombinder. The first encounter was a kobold ambush with loads of minions, two slingers, a dragonshield, and a nasty trap. Beforehand I thought maybe the minion-spam would give the Vampire some trouble, but I played the Vampire as if he knew he was "fragile", using the ridiculous Stealth bonus to hide from the slingers while swatting down minions with Taste of Life. The Binder went down first (taken out by the slingers), the Blackguard one-shotted(!) the dragonshield and was then taken out by the trap, and only then did the few remaining kobolds manage to mop up the Vampire.
To see what would happen after the first nasty fight of the day, I decided to have the party be "captured" and that they could use whatever surges were available to heal up. The Blackguard still had plenty, the Binder had only one left, and the Vampire spent his only surge (and regen'd back to half HP). They were then promptly disarmed and tossed into a cavern to be fed to a fledgling white dragon who likes his meals with a little fight in them. Long story short: after a quick combat that left the dragon bloodied, the Vampire was the lone survivor (if undeath is alive) due to a lucky death save, several Stealth rolls, and believe it or not, the Shade's racial ability.
Anyway. What did I learn from all that? Mostly that kobold slingers are a nasty piece of work. I was also a bit disappointed that the Binder did not seem to work out in play all that well. It's a really neat concept, but in practice they get controller damage, mediocre control effects (push 2, whoopee), and a pact boon that almost never triggers. I really think the Binder was the most fragile of the trio, even with the same Con and nearly the same defenses as the Vampire. Maybe things get better at high levels.
I also learned that temp hp are super awesome. The Vryloka Blackguard had two different encounter powers (Lifeblood and Shroud of Shadow) to get them, and put them to good use. And Taste of Life should absolutely be the bread & butter of every Vampire. The Slam is for OAs and charges only, and Dark Beckoning is very situational.
The Vampire's low number of healing surges never really became an issue, though admittedly this was not a typical play session. But the Binder blew through six out of seven surges in that first fight (healing potion, second wind, 4 more to recover afterward), and it put him in just as bad a spot as the Vampire with none. And the Binder had no temp hp powers, no regen, nothing to help him when things got bad.
But basically, the end message I got is that Vampires are OK. Really, it's only that final surge that matters, and as long as it's there a Vampire can pop back up, regen to half HP, and try Blood Drinker again in the next encounter. That (and Taste of Life) is a lot more than most classes get. Yeah, they're fragile, but so are Rogues and Wizards (and Binders, it seems). Damage was never huge, but consistent. Vampires honestly seem most like Monks, mechanically: specialist strikers with excellent mook-clearing and a side helping of control.
Oh, and PS: Blackguard generic bonus damage plus Fury bonus damage plus Smite damage plus Vengeance Strike bonus damage = one dead dragonshield kobold. Holy crap, he nova'd and I didn't even realize it was possible until the opportunity was right there.