I bought one about a month ago and like it. I had a SkyTach (sold it).
The SkyTach worked well enough, but it had a few annoying "features". The worst of which is that it doesn't have an on/off switch. You move the speed-changing rocker switch to start it up, then you have to wait about 20 seconds for it to stabilize before you can use it. Then just as you're getting a good reading on the helicopter, it times out and shuts itself off again so you have to start over.
Another annoyance is that if the rocker switch is moved while the tach rolls around in your tool box, it will spin up for 30 seconds, then time out again. Over time, these unwanted startups will eat the battery, then just when you need it, it will be dead.
Finally, the SkyTach has a small window that's hard to look though with glasses on. And it's cheaply made. It rattles from all the low-tolerance plastic parts and poorly-balanced rotor.
The Western Robotics, though a bit pricey, is of much higher quality. The window is over 4x the area of the SkyTach so viewing is easy even with glasses on, and the whole device is solidly made... no rattle. Best of all, it has a real on/off switch so it will stay on as long as you need it.
If you can afford it, I highly recommend the Western Robotics over the SkyTach. If you're on a budget, the SkyTach does do the job accurately though it's a bit irksome.
Hope that helps.
You paid HOW MUCH for that?