I recently acquired one for my F2. It meters about the same as my DSLR, so that's a good sign.
My first test negatives came out about a stop overexposed, but that might be a shutter speed issue on that particular lens. I'll be trying another test run soon.
It didn't seem any more of a nuisance than any other metering approach, save that I was a bit paranoid about keeping stray light from the probe. Since it has a shutter that closes off the viewing side when in use, I'm not sure if that's absolutely necessary. But I figured it can't hurt.
Can't speak to durability yet - sorry.
On the whole: I like it.