I think this map is quite good.
Indeed not very original, but it´s more than a copy. One thing I´m really missing is an own theme. Maybe that´s the reason why it looks like a rip-off at the first sight.
There are already some good details, but there´s still space for improvement. For example, I would add some details to huge walls. They look a bit plain.
And for my taste, there are too much pickups. The map is rather small and I wouldn´t place nades, ammoboxes or health in every corner. Especially one place is a so called 'no-go' to me. Here´s a screenshot:
http://www.misterfloppy.de.vu/misc/screeny_obl_snow.jpg
I suggest to remove most of them, especially the grenades. I think two nade-pickups are enough for this map.