I fired a HK VP70Z many years ago (I was considering a purchase of a used one, and a friend of mine graciously offered to let me try his, first).
First, the good news -- it is a HK product, so it works reliably (see note on ammo types, below).
Now, the bad news...
- It has a long, VERY heavy, slides-straight-to-the-rear trigger action that makes it difficult to achieve decent accuracy, at any speed.
- The trigger is shaped to guide your finger to one point on the trigger face, and keep it there. This rounded-V-shaped location is small/crowded enough to make it uncomfortable for some folks who have larger fingers.
- The safety is a cross-bolt style button behind the trigger, which moves side-to-side in the frame (reminds me more of a Remington shotgun or a .22 rifle than a defensive pistol).
- It has a strange/unique front sight, consisting of a wide brightly-polished ramp with a dark groove/slot cut in the middle. The image of this dark shadowed area is supposed to serve the same purpose as a conventional front sight, but under certain light conditions it is difficult to see/use, and it blocks the entire lower-half of any reasonably-sized target past about 10 yards.
- The slide is very large/heavy/bulky, due to the blowback-style mechanism, which makes the pistol very top-heavy in the hand.
- The big slide is matched with a very heavy recoil spring, which can be difficult for some folks to manage when pulling the slide to the rear manually.
- According to various accounts I have read, spare magazines can be difficult to find, and very expensive once you DO find them.
Note on ammo types: The VP70Z I fired was only reliable with FMJ/Ball ammo; it would not get through a magazine of hollow points without at least a few stoppages.
It was a cutting-edge pistol in its day, but that day came and went about 2-3 decades ago.
"Placement is power" -- seen in an article by Stephen A. Camp
(RIP, Mr. Camp; you will be remembered, and missed)