Went to GC yesterday intent on selling a bass, they had an avalanche Jazz Ultra II 5 on the wall that I ended up trading in for at a decent discount.
As a long time Fender player who's owned many Jazz V models from as far back as the 90s (Deluxe through current series), here's my quick take compared against past interations:
Ultra II Pros:
The preamp is noticeably "better", more natural sounding and little to no volume difference between active and passive. The S1 switch is a better option than a tiny switch for active passive mode. This is the first active fender model I've played where the pickups don't rely on the preamp to sound good. The mid frequency switch is a nice touch and very usable.
The pickups sound great in passive mode and don't depend on the preamp being active to sound right. I found with the Deluxe/Elite/Ultra I that the pickups seemed to be tuned for the preamp and lacked punch and high end when run usable.
The quarter sawn neck is definitely more stable so far, and seems more resonant (on this particular bass). The neck profile and fingerboard feel amazing, I can't expound on the difference between the past models as its been a couple of years since I've played an Ultra I or Elite. I liked those necks as well. The luminlay side dots are a nice touch and remind me of a Suhr or high end "fusion guitar" style side dot.
Overall, the bass sounds amazing plugged in, is very resonant unplugged and sets up nicely with very low action (1-1.2mm at the 12th fret)
Ultra II Cons:
The truss rod adjustment is a downgrade from past models. It works fine, but I don't understand why they didn't at least keep the larger T handle nut at the headstock instead of the smaller allen key it has now (or the wheel at the base of the neck).
I liked the block inlays, but the dots are fine as well. I'd say it's evened out, the side dots are really nice if you consider them as a trade for the blocks. Would be nice to see them bring back the MOP dots from the 90s
The bass is heavy. Weight doesn't bother me, but this one is easily around 10 lbs. Wonderfully resonant and responsive, but if you want even a 4 string II at 9 lbs you'll have to search.
The Ultra II is a definite upgrade and IMO the best iteration so far from the last decade, but if I had an Elite or Ultra I I wouldn't be on a hurry to switch over.