I bought an 8x Solo a couple years back (cheap on the EE) specifically to carry in the pocket of my coveralls when working on a remote jobsite, simply to have something handy in case some interesting critter or bird showed up (which happens a lot). It was my first experience with a monocular; it was okay for that purpose, simply because any compact binocular I had carried like that would quickly lost its collimation.
It's okay, but that's about it. Lots of eye fatigue when trying to do long-term observation with a monocular. Awkward to hold and focus. Optics are okay. It's held up well, but I can't see using it anywhere that I could manage a binocular instead.
Actually, I had a cheapo Steiner porro-prism binoc whose hinge broke. I sawed off the entire hinge mechanism; it was an individual-focus model so that was easy. I now have two completely functional monoculars, with focus that can be preset for anything from about 30 yards out. They still have their objective caps attached, and the shape is much nicer for one-hand holding than the straight-tube Solo.