Prakticas are usually very solid beasts - they'd have to be really badly treated to fall apart. If it goes BANG when you take a picture, it's meant to, it's the mirror slap. The lightmeters are known to go sometimes, though.
I have an MTL3 as well as a B200 (broken) and a BX20 (one of the last SLRs they made iirc). I prefer the MTL3 as a camera to look at, hold and use, but the BX20 does have a lot more features, and doesn't have a broken meter.