Having played warlock back then:
1. Talent change yes
2. Warlock will probably be a bit bad (or mediocre) until T2 and T2.5. Then they become middle of the pack, far behind outliners top tier DPS (Mage>Rogue/FuryWar) though.
Two things to keep in mind: as a warlock you will often not be able to go "all in" while DPSing because we hae a threat issue (our threat is high and bursty). And finally like others said, you will often be told that you can't dot (because of dot limit). Gimping yourself even further.
That is mostly the reasons why i won't roll one this time
Beside that, it is a really solid class though, and it excels later on in PVP. Remember to go Horde though, else you will end up getting chain stomped by UD rogues.