I've had the exact opposite experience with both flip cards and vampires. I had a green/white deck that was heavy on flip cards that got me in the top 4 in a large very competitive draft, and then a green/red deck again with lots of flip cards and vampires that did very well until I decided to gtfo and go home instead of being forced to hang out at the store until midnight again.
The flip cards force your opponents to change their play behavior. I loved seeing them struggle to figured out how to cast two spells during their turn just to flip my guy back (and in the process waste a spell or two that they might have gotten good use out of later). Or casting something useless just so my guy wouldn't flip.
And the red vamps are great. The rare 1/1 for 1 mountain is one of the best turn one plays you can have. If your opponent doesn't immediately deal with him, he gets out of reach of burn very quickly. And while your opponent is trying to kill him off, you are dropping other creatures. One of my best games saw me drop that vampire turn one, a green flip card turn 2, and another green flip card turn 3. By the time he killed the vampire, I had those two other guys on the board forcing him to play cards he would have otherwise saved so that he wasn't facing a 3/3 intimidate and a 4/6 instead of a 2/2 and a 2/3. By turn 4 I had a Trepanation Blade out and he knew death was coming next turn.