I'm playing an Executioner at the moment, and thoroughly enjoying it - it's a bit weaker in general than I'd like, but I enjoy it thematically and that's what really matters.
The vampire actually seems to play a bit like the Oassassin, at least at very low levels - they're both fragile, albeit for different reasons, and their powers function similarly aside from shrouds and such.None of my players in any of our campaigns have tried an Essentials class yet. In about one month though, I'll be starting a new campaign for the group and we're slated to have an Executioner and a Vampire played within it.
While I don't care for the lack of options in an essential's character design...I very much look forward to seeing these characters in action. They have so much flavor in their powers from what I've seen from the character builder.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.