looks great! for your first try at scratching that is amazing work! i actually have had those speakers so i picked them and the cup out. besides that great use of parts. nothing that really jumps out as obvious. the only reason i picked out the speakers and such is i like to play a game with myself and try to figure out what others used with out knowing. kind of sharpening my spidey sences for good parts.
now i'm going to switch to the constructive critism. please, please. don't take this as i tearing you work apart. these are just the things that i see that you can keep an ey out for next ime so your next one can be even better. take them as more of hints for later.
first up if you don't have a set of small files you might want to invest in a set. they can be had cheaply at most home improvement stores or online. just look for jewlers files, or needle files. something like these.
http://eze-lap.com/control/wp-content/uploads/2011/10/EZ_NeedleFiles.jpg
they don't have to be this comprehensive. most only come with like five files. all the basic shapes. i say this because of the pieces that you put on the pvc tube neck are sticking up a little. not bad. but you wanted to know what we saw. a little filing to round the bottom of those parts to match that of the pipe, or if you would have used a hack saw or razor saw to cut knotches for the ends of the parts to slip into would have gone a long way. focusing on that same area. you mentioned that you thought it was to sparce in details. not so. this is the tricky area in scratch building. knowing when to say when on greebeling. the only thing i would add if you wanted just a little more there, would be to take the sodier/wire and run a couple "tubes" out to your center details.any more and it risks becoming cluttered.
actully the whole ship could benifit from a little use of this technique.you have a lot of holes in your different parts that could have piping going from one another. just don't do straight shots of line. route them in z patters and such. basically rout them inbetween and around panels for the most part.the melenium falcon,the corvette ship from star wars, and the battle star gallactica are all really great examples of this. just look of reference shots of them and take a look for ispiration. they seem to be the type of ship you are gearing towards.just don't go over board with the piping or you will ruin the look of your ship. like i said fine lines. what i do is add a little here and there. step back a couple feet, look at it. if it needs more i add it. if not i leave it alone. and symetry on the part of tubing is not always necessary. depends on how nice of a ship its supposed to be.
the other nit pick i have is on you forward sectionon, on the bottom, you have an antenna array/cannon assmbly there. the straw tube that you used. i'm going to guess sucker stick of q-tip stick. is all one size. i would have found a tube that was just a tad bigger or a thinner piece to go inside the tube. bigger to ut out pieces and fit them over the tube to break up the lines. or a thinner part to step down and be a point on an antena. but something to break up the one sized tube lines. but that's just a minor pick.
another thing that i notice is that most of your pieces are just one piece added to the outer hull. don't be afraid to layer parts. or add one part on top of another to make it a whole new piece. take the gearish looking pieces at the very front, top section of your back section. putting the back most one ontop of the forward ones would have been cool. or maybe something like a hub cap or gear on it. or another piece on the inside of it. it helpst to have tons of parts laying around to play with. i understand that you don't.(yet, cue the meniacle laughter) but stacking details can really change the look of one neat part into that one awesome part.
now what can really make all of this pop is in the painting process. a good light color with a good aplication of grime washes and pastelles can really bring this to life and make everyting stand out better. so watch videos on how to do weathing or read walkthroughs. adam savage does some great ones on his one day builds on youtube. you have to kind of hunt and peck for the gems. i really wish he would do a series on all of his modeling knowledge of wright a book.the man has amazing skills.
that's all i could really see. like i said in the bigining mostly nit picking just to draw your attention to how it can be "upgraded". i saw nothing there where i would say you messed up or missed the mark. mostly small detailing. your off to a great start. just to warn you. this stuff gets in your blood. and oce it's there it never goes truely away.lol
also, just as a p.s. you are going to see these guys in these vids with a bench full of tools. you don't have to have all of that. most are just niceties. that we get after years of doing this. you also don't have to run out and get them all at once. right now is all you really need is a good set of crafting razor blades(didn't want to say exacto for fear of you thinking that were the ones you needed to buy, any of that type will do) mabe a pin vice(hand drill made for small bits
http://www.modelcrafttoolsusa.com/1...uble-ended-swivel-top-x5-drills-ppv2237-d.jpg ) a good metal straight edge, pencils, glue of choice, and maybe a razor saw. long off goal might be a decent dremel like product with a flex shaft. once you have one you will wonder how you lived with out one. but i would wait to see if you want to stick with doing this first. since your at the painting stage i would recomend a thing of cheap water colors for wethering and mabey a cheap box of non oil pastells for weathering powders. but really build up over time. you will be able to tell what you really need and don't.
this and starshipmodeler.net/talk/index.php are great areas for sci fi ship knowledge. keep us posted on how this ship and any future ones go.
every time i tried to shape it it just came out really crooked and not very good looking. on top of that i realized i had no idea how to adhere it to the plastic, because the model glue i bought didn't seem to work with the metal. Eventually frustration got the best of me and i decided that would be something to do for my second ship lol (plus once i get it down there is no reason i cant still add some onto this one) 
