Ah, that last picture was a bitmap. People do NOT like bitmaps for screenshots: you get almost no improvement in quality, but 10x the download time. Since your first pic was a jpg, I assume you just made a mistake.
Okay, with only 2 shots to go on, I can analyze each shot in detail.
First screen: Bare, bare, bare! You have a big wide space, and nothing in the middle. Always ask yourself why this space was created, what it's for and so on. If it were a community hall or a dancefloor, there's good reason for it to be empty. But this room looks like it's being USED for something (lockers, crates, funny blue sci-fi cylinder) so it should look like it's used. Put some tables in, and some lighting, and make it feel more natural. Plus, it would be nice to see some custom textures or even models (although I realise that, if you just got FPSC, you wouldn't have got round to that yet).
Second screen: This is more interesting. The floor and walls are nice. I'm not sure why there are boxes floating in the middle of the room - is this a shot of a sort of explosion? Or are they hanging static in space? Either way, as long as you explain why, it's fine.
I'm not actually a Kiwi, I just randomly thought it up one day.