The idea behind the Vindicare, is that he can assassinate one enemy quite well if he needs to. Like the Ogryn, he can generate 6 character tokens, that boost his combat abilities: however he doesn't create an auto 6, instead he adds an additional die. This means he can still roll a 2, while the ogryn will roll at least a 7 when using his ability.
The other special ability he has, allows him to stop enemies from ganging up on him: or turn a fight into a cunning test essentially. By using the assassinate you can turn a fight where you would face 2 enemies that combined would defeat you into a much more manageable fight, or use it to tackle enemies who have high stats that you do not (such as willpower).
Both these abilities are great, and useful most of the time- but both can fail and do NOTHING at all. The trick to playing him well, is to really time your uses of the special abilities to when they are vital, but have high chances of success. combining this with good power card usage is the key.
The last ability gives the Vidicare a 6+ invulnerable save if you will... it can save him a few life points here and there, but it can also give him an alternate way to generate tokens. We found that giving him this ability generally only creates 1-2 tokens per game, but it gives him an open ended feel: because he is highly dependant on his tokens to do amazing things.
Right now, he does very well mid to late game: but if the game goes on too long and he runs out of tokens before making his final run, he does suffer.