Those images highlight an issue a lot of fan ages have I've noticed, which Adam mentioned previously which is lighting (I should point out my own Ages are far from perfect

).
Now, when I talk about lighting I don't just mean providing light sources. Lighting is more that a light source. When a bulb is turned on not only does it make the room brighter, but it bounces off surfaces and objects. A light next to an orange will cause an orange light under the fruit. But it also casts shadows which are not actually black.
In Uru you can pretty much get away with black shadows, sure you could be really finicky about it but often black will suffice.
The first 9 images don't look too bad, this is namely down to the use of Cyan's textures. But there is room for improvement. Objects such as chairs and desks aren't casting shadows. Nor are there gathering shadows in corners of a room. Now granted corners aren't always shadowed, it depends greatly on the light and where it is placed in a room.
For example, here is a quick before and after mockup in photoshop;
BEFORE

AFTER

Note the book which is very bright in relation to its surroundings. It is always worth checking your textures to make sure the follow a similar brightness (depending on what you're using them for of course).
Some times I'll directly paint light and shadow effects right on to a texture in photoshop if need be, a lot of the time I use lightmaps and vector painting.
The last image is definitely a good example of needing some tweaks with lighting, again a quick before and after photoshop edit;
BEFORE

AFTER

Not in anyway perfect, but it was a quick edit in photoshop to illustrate. It always pays to study the real world around you, study how light and shadow effects objects, colours and textures and it will give you a good guide when replicating within Uru.
As a side note, that last image. There is an awful lot of the same rock texture being used. You might want to look into mixing it up a bit. D'ni actually has several rock styles used a little alpha blending with some other rock textures will break up the repetitiveness going on there

Hopefully I haven't offended anyone with this, I figured I'd pass on some thoughts of how I tend to approach Age building.