Thomas summed it up well.
My 2 cents...I own one of these, and for the fabric bits, it IS decent. The belt I didn't bother getting from them because it's terrible, I bought mine elsewhere. I've been meaning to upgrade my greeblies for forever because they're pretty much 3 washers and a screw in costume-base's hat. The rankbars are a joke. They're made out of grey, red, and blue rubber. But they come with it, so it wasn't any extra $$, and it didn't cost much to get better ones.
So this is my Imp officer with the added components of real riding boots, a nice belt, chalk holders, and a good rank bar:
(Yes it's baggy, but keep in mind this is a men's medium, and I'm a women's 0-2. >.< That tells you how versitile the sizing is!)
As for approval.....as far as I'm aware I was one of the last few people to be approved with the *unaltered* Costume base imp officer (soft parts only). I may be mistaken but the officer's detatchment has gotten quite finicky (more power to them) and unless costume base improved their outfit it most likely is NOT approvable. Heck, I don't even like how I look in it because it's SO baggy on me, and a lot of people have had sizing issues. To make it really work, the way Jamin did, it needs to be altered in most cases. In 501st terms, it's basically the less expensive version of getting a Rubie's vader and working it well over.