I’m a newbie at Blender but not at 3D in general, so I’ll give this a shot. Firstly, I must say that the objects are beautiful. I’m especially impressed by the hour glass. It is one of those very often rendered objects but you have managed to make it very interesting - the glass and sand look great.
Possible improvements:
A continuation of Modron’s comment. The floor looks a little unfinished compared to the very intricate objects you have created. It could simply be that the texture has been scaled up too much and lost detail (like when you resample an image up too much in Photoshop with the bicubic setting). A higher-res texture might help.
Due to the particular camera angle and lighting setup, the shadows of the objects on the floor are almost invisible compared to the total darkness at the edges of the scene. Stronger (and more obvious) shadows might help anchor the objects to the floor more convincingly.
I’m sure you have seen that optical illusion with flat shaded cubes. When you have a bunch of cubes stacked in a pyramid, your eyes are not quite sure wheter they are cubes or cube shaped depressions. Something similar is hapenning with the watch. Due to the dramatic lighting, all you see is an oval shape. While I know it is supposed to be facing the left, it could just as easily be facing right as just an oval shape in 3D. If there was a (very mild) fill in light somewhere to better define the depth of the watch on the right side, It might add more volume to it.
Hope these comments are helpful. It is a great image, and I look forward to seeing you progress with it.
I like the movement you have in these renders really like the second one, Has a really good ballance to the white areas but I’d like to see a little more of the roses Really good
The only comment I have is that the sand in the bottom half of the hour glass looks a little odd. As it falls it tends to form a straight sided cone - in yours it looks almost viscous - you wouldn’t get the inward curving peak.