For the most part, most MMO's are" rip-offs" of World of Warcraft. Don't care what anyone else says, at least some of most MMO's these days are based on WoW.

Warhammer Online's third-person perspective? Used in WoW. Scenarios? Battleground equivalents. Classes? Also in WoW.

All these aren't game breaking though. What my point is, is that SWTOR may have a few elements of popular MMO's (such as WAR, WoW, LotRO, etc), probably the most common and/or popular (such as the third-person perspective, the similar archetype for classes, how PvP works etc) then BioWare will add features not seen in the other games (classes may work differently? PVE and PVP content may be similar but have "twists" etc).

In this regard, almost all modern MMO's are the same, but very different. Not all of them have the same storyline (granted, Warcraft is just a big-ass Warhammer rip-off but it does well at being one, I don't need evidence to show this, the 11,000,000+ players does that for me), not all of them have the same classes (such as Warrior, Mage, Priest, same archetype in the end of it all but just portrayed differently).

PVP is different. WoWs Battlegrounds and WARs Scenarios are similar in how they work. You can queue for them anywhere, it's realm-vs-realm. After the facts, they're pretty different, rewards are different, objectives are different etc.

To conclude: BioWare's SWTOR game WILL be like WoW and WAR in SOME respect. So you WILL get people that will go "this is just a WoW/WAR rip-off but in space! WHAT THE FUCK!?", since people are douchebags and love to complain about EVERYTHING. But overall, you'll notice the differences and you'll either hate 'em or love 'em.