Can't claim any experience of Kamaz, but we bought (for evaluation) a Kraz who are the Ukrainian equivilent of Kamaz - i.e builders of tough, rugged trucks in various off road configurations etc. On paper it looked great: 6x6, 370hp V8, super heavy chassis and suspension. I am so glad we didn't buy more - complete piece of crap, after 2000kms on gravel roads it had:
cracked radiator mountings
radiator header tank snapped off!
Diesel tank started leaking at the seams
It appeared to be made of recycled baked beans cans...
Shortly after the first service (5,000kms) the chassis was cracking and the gearbox was stuffed - that was three months ago... still waiting for parts to fix it and sell it! a 13 year old MB 2624 is more reliable.
Now kamaz might be a totally different kettle of fish, but I cannot see their regular trucks being any better than a Renault Kerax, MB, MAN etc but probably a bit of a parts nightmare?