Toonami just keeps rolling out the hits it seems, first Gurren Lagann and now this. :fistpump:
Hellsing Ultimate is all around awesome to anyone who enjoyed the original TV series since this one is actually more faithful to the manga and thus has a MUCH better story after the Luke Valentine incident.
What happened was a similar case to Trigun and Fullmetal Alchemist (original anime) where the story diverged from the manga at a certain point, in Hellsing it was after the Luke Valentine incident and in Trigun it was after the meeting with Legato.
So yea, you do not have to be familar with the original series to get into this, it adapts the first few episodes from the original series as well as follows the manga after the Luke Valentine incident which is MUCH better than what the anime team came up with.
I watched the anime, but I don't remember what happened (it was a few years ago when I watched it). Though I do remember Hellsing Ultimate's story. (I watched it subbed though.)
And unfortunately, for better or worse, I can't watch an English dub without thinking of Team Four Star.