Ninja, way better than every other class.

[Allyrion]

I think that might be a big part of the appeal for people jumping ship from MNK, actually. Both jobs, you have a lot of abilities available:

NIN: I wanna do this thing. (Does this thing.) Booyah!

MNK: I wanna do this thing. Eh, can't do this thing yet, GOTTA KEEP STACKS! (Keeps stacks.) Now maybe I can do this thing? No, the window has passed, and it's no longer an awesome thing to do. Dang.

Everything MNK is tied in extricably with its GL heartbeat. While you do have different things you can do to maintain that heartbeat, and abilities off GCD that you can weave in, you're still its slave. For many, going from MNK to NIN represents FREEDOM.

NIN certainly has more wiggle room.
That said, they're held down by quite a few timers themselves which are more of a consideration than it is for MNK since the combo naturally keeps everything up.
ToD is the only damage move outside of the stances, unless you use Fracture (which isn't worth it really). Off GCDs should be used within the GCD, so they don't really affect GL.

Don't get me wrong, NIN is much more flexible, particularly with burst, but Fuuton is pretty much our GL.
The Mudras are only 20s apart and the dots and slashing debuff are something you actually have to monitor to some extent.
NIN are just a slave to many masters instead of one.

Don't get used to NIN skills that much since they are getting some slight changes once the expansion comes.

Not that much. Interviewers and developers alike have said NIN is getting the least shake-up since it's more recently released.
Our old skills don't seem to change much other than getting positionals added to them.
Otherwise we're getting some additions to the rotations but it seems it'll just be some extra stuff to weave in.

What I'm saying is it wouldn't be wrong to learn the current rotation, and then when the expac comes around the OP could weave the new stuff in with a good foundation.
Learning the current foundation is still good because everything has implied that foundation is being built upon rather than changed.