I think my ZM 35mm 2.8 is, as far as build quality, exactly what I'd expect for the money...or maybe a bit better. For me it's not a lens for life, but I'd be pleased to get 10 years out of it with heavy shooting. With that, I've no problem at all handling it, and actually prefer the slightly looser focus pull for focusing speed and ease. There is no wobble with mine.
Otherwise, it's an okay piece of glass. A lot of fall off (the biggest let down), and not as sharp as I was expecting after hearing raves...but it has a beautiful palette. A bit old school for me at times, but I was coming from Nikkor glass, not Leica.
They're a good value, but I would be sure to test the lens to make sure it's the look you want, since I found it to be rather distinct compared to other lenses I've used over the years.