I'm sure it will take several games to get used to all the Specialists, but the feeling I had both before and after playing this first game is that there are too many kinds. I found myself constantly looking them up.
The other concern I have with them is that Elder seems like a god unit. I started discussing this with Ron in game after Noel killed me with one. Then I looked it up again and realized you get 2 for 1 hire! I'm fine with them nullifying the majority of the other specialists, but they should have some weakness.
Consider the board game Stretego. The strongest piece on the board (1 or 10 depending on the version) can kill practically everything, yet is still vulnerable to attack by the Spy or by running into a bomb. Perhaps an Assassin should be able to attack an Elder, or a Guard Dog defend against him.