I don't think it is a failure... well,certainly it is not a humongous success for sure, but it still has active players. I have a few friends who still play it.
Now if the expectation was that SWTOR was going to be the WoW killer,... well, that is pretty much settled as impossible.
I really hate when new games, with new features, are announced and get right away be named as the "Wowkiller": it's a guaranteed recipe for disaster;
Games are overhyped beyond reasonable levels and fail to retain players after the first 2 months, after launch.
Being called wowkiller is not a good thing, for a videogame.