It reeeally depends on your definition of RPG.
This is an MMO, no question there (well I guess SOME question, how massive is massive?) but for tons of players on the server, well, yeah it has that.
As for RPG, well, sorta. It's a game with stats for individuals, that go up with experience and you have some control over the way they grow. How is that not an RPG?
Answer: It goes more into 'wargame' territory. Is Blood Bowl an RPG or a sports/wargame? You have players, they gain experience...they get killed off and replaced with frequency... still RPGish. What about Warhammer, where Blood Bowl it derived its setting? Not RPG as they don't gain experience.
In modern parlance "RPG" seems to mean something where in-game individuals gain abilities over time. Which this is. Or specifically, a system where your match with Bob has direct influence on your match with Joe the next day.
If an expert player who makes a new character/team/etc and plays it for ten hours has an advantage over an expert player with a totally new team, well, it's an RPG.
Even saw an RPG mode in a Quake 1 mod (Future versus Fantasy) where you gain levels and keep them through maps, even if they're not saved on the server... Still definately RPG. And then there was King of the Server for Quake 2, which DID save your stats on the server.
It's enough to make me wonder why RPGs are so popular. They take a simple system and then force the player to invest massive amounts of time in order to keep up. On the other hand, when you're successful you get rewarded long-term... Convincing substitute for real life I guess.
I should stop ranting. This game looks neat.