Skier: 6'1", 160lbs. Technically proficient on any terrain.
Setup: 185cm, Marker Baron binder.
Daily use: trees, pillows, chutes, & tight technical terrain of S. Lake Tahoe.
Of the dozen or so "fun shaped," rockered skis I've tried in the 115mm-ish waist category the JJ is by far the most balanced design: it excels in soft snow & is still tons of fun in mixed conditions typically found at resorts. Float is awesome, pivoting & smearing effortless, and the cambered section offers fantastic edge grip on hard snow for a ski this wide and light (9.8lbs in 185cm).
My daily skiing is in tight, technical trees, chutes, spines and pillowlines typical of the resorts & backcountry of South Lake Tahoe. While I don't ski switch outside of the park, I do find the rockered tails useful for tail drags in tight spots where you want to keep it on the snow and for wheelies to help get the tips up and over larger obstacles.
For skiers of similar weight & w/ the technique to lay down good, carved turns on hard snow, I'd rate the "speed limit" around 40mph. The ski will go faster, but like most other tapered, tip & tail rockered skis of this width, you'll begin to feel the tips & tails flatter at high speeds when slopes get icy.
Caveat: bigger skiers (~180lbs+) looking to ski wide open spaces flat out & blast through heavy crud should look elsewhere. Blizzard and Volkl make flatter-tailed, stiffer, big-mountain skis better suited to your needs.
Punchline: Do you want to go deep, tight, & technical? This is your ski.
Note: *For the 3-star reviewer who complained of tail "hookiness" the problem was definitely his tune: skis with tapered tails & shovels need to have the edges detuned fore & aft of the widest contact points.
I'm a former shop tech who tunes his own skis. Get the right length (go head-height+, they ski short), tune these skis properly & keep the edges sharp, and you will be impressed with the edging capabilities of this powder ski.