I had BW Kampfrucksack which I bought off ebay Germany very cheap.
I liked it & it's rather old fashioned design but it was very unpractical. It is described everywhere as being 65 litres but it certainly isn't. I'd say more like 50L (& I'm being generous), the side pouches are small too, around 2 litres each. For me it was too big for a day sack & too small for a rucksack. It has no back system & the shoulder straps are very basic, no waist belt only a strip of webbing to stop it from swinging. Very uncomfortable with any weight in it.
Reasonably well made (not to the standards of the PLCE bergen though) & the 1000D cordura fabric is of good quality.
Since it was unusable I sacrificed it to make some mods on my bergen.
As Greek said there are a lot of crap copies about as it's a very popular bag particuarly with the paintball fraternity so be sure to get genuine military issue if you do decide to get one. Don't be afraid of second hand either, have a look around.
Hope this helps .............