Sammael, the Master of the Ravenwing is the only character in any imperial codex that has a jetbike.  For this reason alone I love Sammael.  Like the other characters, Sammael suffers from nerfed stats.  He also is a bit expensive to field.  However, let's look at his positive side.

First and foremost, he rides a jetbike!  I don't know why, but I am absolutely in love with this.  He has incredible mobility, and with 6th edition, he gets a lot of added protection thanks to jetbike rules and a true toughness value of 5.  He also has an Admantine mantle which makes him immune to instant death along with a 4+ invulnerable save.  He also has the most accurate plasma cannon in the game and does decently in assault as well since he is armed with a master-crafted power sword.

His biggest draw back, besides the point cost, is obviously the fact that he is not an independent character and so, he can be singled out and will fall to concentrated fire.  Considering the fact that you pay more than 200 points for this character, I think this was truly a disservice, especially considering that he can not even take advantage of his own command squads perks.

Additionally, Sammael has the option of being fielded in a Land speeder.  Whilst this speeder is armor 14 on the front and side, it is simply not nearly as survivable as Sammael's jet bike thanks to the new vehicle damage rules.  I personally, can not see myself fielding this lands speeder.  Sammael also allows you to take a bike "command squad" and allows for bikes to be fielded as troops, thus allowing them to be scoring units.  As mentioned earlier though, the command squad loses some of it's ability due to the fact that they can not be joined by Sammael, but still provide a nice hard unit to the army in general thanks to true Toughness 5 and the new Feel No Pain rules (They only lose Feel No Pain to Strength 10 weapons now).  Sammael, is a no-brainer in Ravenwing lists, however, if used smartly, I could also still see him finding his way into a few lists even if bikes are not included.