I used one of those for many years, buying my first one, as a kit including some bits and pieces, when they were around £50 !!
It was used mainly for large areas, and single colour applications, and was fine. Yes, you need to mix more paint than in the gravity feed types, as the feed tube needs to be immersed in the medium, but it's not too bad overall.
With a bit of practice, you can get down to a line about 4 mm wide, and it'll just about cope with a heavy Luftwaffe mottle in 1/32nd scale - anything smaller requires a fine-line 'brush.
It's a good basic 'brush, or more correctly, a mini- spray gun, and works well. the biggest disadvantage is the cleaning of the jet and nozzle, and the limitations on control, but these are not major issues.
Until about 18 months ago, I used propellant cans, then bought a cheap, basic compressor. The latter pais for itself after about two models, as the cans drop-off in performance as they empty, and of course quite a bit of air is used in testing the paint viscosity, and for cleaning.
Bottom line is, it's a good general-purpose 'brush, and I'm thinking of getting one of the cheap copies, just for large areas and things like clear coats.