I have played all the levels nf and ff.. nf itself I don't like, seeing it has nothing that makes it worth playing imho, ff is just much better, and so playing nf when you could play ff is just a mystery to me. (well nf guns, I can see the point in nf sabres..)
As for levels, nf or ff bespin and bod aren't in anyway great in terms of gameplay imho.
the maps dont flow too well, they have focal areas that you can't avoid, stupid little rooms that are death traps that you have to go through for normal movement. there are much better No Fun^Wforce maps made by the community, or in Q3/UT/other nf games.. which are on a whole much better then nf jk.
BGJ I can see why people like it for ff, I just never liked it as much as Oasis.