I have a 166B and I think it's pretty well made, on par with Japanese TLRs that I've owned. It could use some new lube but otherwise in good shape. The shutter works despite probably never having been service and the film advance gives you a pleasant feedback from what I assume is a ratchet wheel inside the knob, unlike the Seagull or the Lubitel 166+ where the advance knob just turns smoothly without much haptic feedback. The Lubitel is very light (about half of a Yashica Mat or Rolleicord) and has a lower profile and more rounded corners than most other TLRs. The lens is capable of producing decently sharp images as well as lo-fi lomography. There is some vignetting when shooting, say, blue skies wide open but it's not a problem I usually run into. An old 40.5mm lens hood can be used to improve contrast and help with flares which the lens is somewhat prone to.
There are, however, some drawbacks. It can be very tricky to focus the original Lubitels due to the ground glass spot being so very small. It's been suggested to treat the ground glass like an inverted split-prism, i.e. trying to
make straight lines match up at the edges of the ground glass spot. It's important to keep in mind when composing that the viewfinder only shows 80% of what the taking lens sees. Another problem is that, particularly on the 166B, the shutter release lever is somewhat diminutive and also has some sharp edges. This can be remedied by using a cable release (which also reduced camera shake stemming from the Lubitel's lightweight construction) or one could try to melt/hot glue a plastic button onto the release to make it more ergonomic. The release is also right underneath the cocking lever so it is possible to fumble and fire the shutter right after cocking it.
I also have the Lomographic Society's improved Lubitel 166+ model. Basically, this model introduces a flat fresnel focusing screen (Jinfinance or similar) that covers 100% of the image and makes precise focusing pretty easy. There are a number of other improvements but the focusing screen is the most important one, really. Like Lomography's other cameras, the 166+ is not exactly cheap, but then again, it is also very much a niche product.
All things considered, I really love the Lubitel for it's simplicity, low weight and soviet charm. It is my go-to travel camera because I can have medium format without lugging a >1 kg brick around.