And I love it!!

I'll try to keep it very brief instead of a rambling review. I've had it on 3 gigs now and many practices. It sounds FANTASTIC - especially in a live mix! One of the best sounding basses I currently own. Wasn't expecting that from a sight-unseen purchase. It plays effortlessly - and it's an extremely well built instrument. The fret work is very good - I can get a very low action and the fret ends are well done & do not protrude past the binding. Super smooth along the neck.
The tone is fantastic - it's growly & punchy! Which is my cup-o-tea. I LOVE the fact that the designers at Jackson decided to make the 5 string version a reverse P at the neck pickup!

The neck is very thin & fast playing - on par with Ibanez SR series, but also re-inforced with graphite support rods & dual action truss rod. It's solid but it's not gonna be everyone's cup of tea. I like it a lot, but I also own other necks with the same feel.
The bridge is definitely high mass - I'm guessing this might also help contribute to the wonderful sustain this instrument has too. The preamp IMO is outstanding - can coax just about any kind of tone you're looking for from it. Very warm/smooth to growly/punchy, clank/bite, it's all in there.
Couple quick play-along bass tracks to give a general idea of a couple tones.
Both pickups (preamp flat).
P-only (with cut mids & treble).
So there's that.