sorry im a bit late on commenting on this but ive been feeling so bad recently *cough*cough*....
i had a quick sprakk at the screenies, and if this is your first map, id be chuffed. its better than many ive seen (some ppl release several maps of lower standards...then they finally seem to click what is a good standard).
its already been covered, but the lighting is ...well, absent really. just chuck some in to get a basic ambient light and then fine tune where you specific lighting. thats what i used to do, to get some lighting quickly set up. if you wanted to be adventurous, cut some hole sinto the roof, make a skybox and use sunlight to create some advanced but simple looking light effects. Upping the shadow detail in the surface properties (its the box with numbers in it, set to 4 for max detail) would help to create more detail also.
On the subject of surfaces, the best trick when your new is when you apply textures to surfaces, hit shift+T to select all matching textures, and go to propties and hit the alignment tab. then go choose from default, planar ,box and theres another selection (cant remember). this aligns all your textures automatically, and often saves a lot of hassle in aligning borders etc. it doesnt always work, so be prepared to do it manually using the align texture tool.
Theres a lot to learn in the editor and its well daunting at first, but you'll get the hang of it. the two tricks above should help you raise the standard of your map and future maps with little effort.
i agrre with loq on the 3-5 maps thing, but dont take it as gospel...i reckon boneyard was received pretty well and that was my first ut2004 map, and my 5th map ever. Just learn from the pros, open up some pro maps and see what ideas and techniques they use. sometimes they are better than 100 tuts.
its a bit of a rant now,hope it helps.