I really don't get why people play a single race. Random gives you a lot more game to play. Unless you are trying for tournament level play... I just don't see it.
As for Kerrigan voices? I only played the first part of the original Starcraft fairly recently, will get back to it at some point... but really the story and voice acting wasn't doing much for me.
Wings of Liberty I thought was pretty decent. I was worried that the transition to the Zerg would add a level of hokeyness to the proceedings that would kill it, and sadly after the first 5 missions or so I think I was right. It's just so cheesy and lame. They can't write good dialogue for an insect race. The writing was on the wall with the silly Protoss levels in WoL so I'm thinking it'll be pretty bad in the final chapter as well.
Some of the levels have been decently fun, so I think the gameplay will still be there... but the story went from decently engaging to disaster.
Oh, and I like Tricia Helfer's voice. It makes me think of BSG. Brings a smile to my face it does.