Hi, yes the QUARZ is a nice little camera. Since it's a clockwork drive all metal camera, it weighs a bit more than most other Super 8mm cameras near its size. However, the Meteor manual zoom lens is quite sharp, the camera focues easily via the crisp microprism focusing center circle in the viewfinder, and the built in light meter is pretty accurate for most purposes. The camera has several running speeds as well as single frame (via cable release socket only). The camera often sells under $100 on eBay and is a great bargain, as long as it works. Some have been known to jam, but this is rare. Similar in its internal robust construction to the K-3, i that if it should jam, any repair tech could put it right again, or gentle or firm nudge will usually coax it back to running. I personally haven't had any troubles with mine in the years I've owned it. However, since I do have many cameras, I haven't put tons of film thru mine either.
The removable zoom lens leaves a 15mm fixed focus prime lens in the camera body. While the screw mount is a C-mount, you can't put just any lens onto this camera, as you have to factor in the prime lens. So any addon type lens that requires a prime lens behind it will work, via any necessary adapters. Some examples: an anamorphic lens(works great as I have done this many times), an addon type fisheye or ultra wideangle lens, macro type closeup lenses, and other similar type lenses that do not have builtin aperture adjustment(otherwise you'll have to leave it full open, and continue to use the builtin aperture in the camera body). I suppose theorectically that if the interior prime optics were removed, it would be possible to collimate a C-mount standard lens or zoom to the body, but this would all be quite a bit involved costing many times more than the camera alone. If that is what you need, lens interchangeability, then pick up a working Beaulieu. Oftentimes the sound models [3008S or 5008S] will sell for far less than their silent counterparts. Back to the QUARZ, the only real hassle with this camera is the handwind mechanism which will tire your hand out even after just a cartridge or two. If they had made an easy to use winder similar to that of a BOLEX H series camera it would've been better. I have seen a crank winder made by someone in Australia to retro fit to the K-3 and figure something similar could be done to the QUARZ Super 8mm camera as well, but I haven't gotten around to that project.
With the zoom lens removed and the handle grip, the camera body has a very compact profile. I have used it also with very small wide angle addon lenses which were made for various other cameras such as still film cameras. These have converted the builtin 15mm to anywhere from a 4mm to 8mm range effective focal length lens, and yet still maintaining a very compact type package for filming on the go. Even just using some good grade electrical tape to hold such a lens onto the body for short term use works great in a pinch. I have also filmed thru binoculars and so a monocular telephoto lens would probably work great too. I have never met an owner that didn't like the camera. Most Super 8mm filmmakers own several cameras for several different uses; travel, family, artistic work, animation, title making, experimentation, and for more complex filmmaking. This camera can serve several purposes. Again, keep in mind that the winding it up each time might get old. I have always used clockwork cameras from my childhood beginning with Double 8mm (aka Regular 8mm) and don't really mind winding them up. However, on a tripod, doing a film project, I can see how it would bother some folks quickly. Lastly, it's worth the low price you can get these for, and you can have a lot of fun with them. Just don't use it as your everything camera, as there are others out there that run on batteries and would be easier to use for other filming. Good luck!