I actually like the Z shaft quite a bit. When I first tried it I had been shooting with a 314 for a few years prior. Then my cue was stolen and I had to replace it, so I tried the Z.
At first, the Z had so little deflection that I was missing shots by over compensating. I adjusted, and started to play very with it after a few weeks. I can understand why so many people that try it don't like it initially. Most hit less than a dozen shots, before deciding they don't like the hit. They judge it on feel primarily and their success while trying it only briefly. It does take more time than most shafts to adjust to, and it is a pretty stiff hit.
I like it becasue I can achieve shape effortlessly that would otherwise require a hitting the cueball so off center that you are in jeopardy of a miscue with another shaft. That is the beauty of the Z. You don't have to hit as far from center to get the same cueball action. Just hint at some right english and you'll get plenty. The Z transfers more spin than most can handle. The downside it that if you strike the cueball off center at all, you will miss badly and walk away from the table scrathing your head. On the plus side, if you are an extreme precision player that likes to keep his game very compact, like me, then it is like a razor versus a butter knife.
I also like to play a lot of draw. I will stop balls when others will go three rails. Sure, they play the shots more naturally (by this I mean alter the natural path of the cueball less), and it looks fancy and all, but they also go two rails and scratch, or go three rails and park it behind an opponent's ball. I can go multiple rails too, but I have a much better out percentage when playing compact, direct and simple. They will let the cueball travel 5 or 6 feet and park it plus or minus 8 inches from their intended leave. However, I will only allow the cueball to ge 5 or 6 inches and will leave it plus or minus 1/4 inch.
Furthermore, I can kill a cueball as good as anyone on a cut when using the Z. I can also draw backwards on a cut (to some degree). A lot of people don't even consider drawing the cueball on a cut because they don't hit crisp enough and can't get enough action. The Z is also superior for stun shots, which is another underutilized position shot.
Having said all this I should mention that I much prefer the congestion and precision of 8-Ball to the long strokes and pattern play of 9-Ball. This may be part of the reason I like it too.