7/10 materials
7/10 aesthetics
6/10 lighting
5/10 quality
3/10 difficulty
Really interesting designs; it's clear you have an eye for proportions, composition and color. The materials are well executed for the difficulty level, no clear UV mapping issues, interesting use of multi-ID materials playing on the geometry of the torus shapes. The incorporation into the UI design makes me wonder how design adds to brand, but since there's no clear subject of the website mock-up, that's neither positive nor negative, so I'll leave it at "interesting to look at"
The lighting has conscious thought, and good effort in varying color, intensity, and composition. However, it is overexposed in a few places, namely on the submarines, and the self-illuminated materials on the torus shapes. The blue flood in the second image nearly blends the backside of the torus into the background, which in and of itself wouldn't be a negative thing until you get to the base where the torus clips through the plane, and the intersecting geometry becomes unnatural and jarring from not being blended as well.
The quality suffers from the very clear low anti-aliasing on the edges of your alpha channel. A couple of quality issues should be corrected in post using photoshop or something similar, including the location where the torus clips through the plane in the second photo. Another quality control that would improve the image overall is adding post-render effects such as DOF.
As for the difficulty, this isn't a negative note, but the shapes are simple and geometric without much alteration to the basic shapes you started with. Finding ways to include organic shapes would give it a kick in intrigue, as well as improve the apparent difficulty of the piece. Adding variance to the repetitive shapes would also increase intrigue overall. At least an alteration to the orientation of the repeating elements to break the monotony.