All of us can agree that the levelling in SWTOR is fantastic unless you a player that's not into storylines and just wants to hit cap fast as possible.
So going from 1 - cap it's probably the best mmo out on the market so far and for players that like to level alts in wow I think you absolutely love this game.
PvP seems like it will be fun and I am sure more things will be added in the not too distant future.
So what is SWTOR biggest downfall which is the same reason all other MMOs fail... Endgame PVE content.
For most wow players that have quit in the last month is because they are bored of 4.3 already due to having killed all the content in LFR, now SWTOR normal
mode is equivalent to wows LFR with one major exception... you have no real gear requirements to go into the operation and they easy enough to clear on normal mode. Players have been clearing operation content in questing gear even skipping flashpoints which leaves a big gap in what is required for your charactor progression. The dumbing down of wow raiding is why a lot of players have left and from the looks of it SWTOR is even easier.
Not many players will care for nightmare mode either unless it offers something different...