They are a pretty capable lathe, and hard to beat in terms of capability for price, but they're far from perfect.

I've had a CL500 (the milling head lives under the bench, as it was only ever fitted for a couple months) for well over 10 years now, and it gets regular use.
I machined a new support block with two AC bearings for the z-axis leadscrew, as the original bushing setup was rubbish.
The x-axis has a similarly rubbish thrust setup, but it's workable. I keep meaning to fit a longer grubscrew with a either a locknut or a bit Loctite so it might actually stay adjusted.
I could never get the saddle to adjust with minimal play and no binding (you'd tighten the gib, then it would bind when trying to move it, yet still wobble about), until I finally stripped it and found the gib strip was bowed. Replacing it with a suitable bit gauge plate solved that problem.
The change gear setup really is a PITA to use if you want to do threading.
Changing belts is also a bit a nuisance.

Biggest improvement I done to mine was fit DROs.