Poseidon

My first immediate thought, the background wall, door and plants are very well done. The stone runner provides a really nice transition as well.

The statues however leave me a bit off. It is hard to put my finger on why, but I am going to give it a shot. This purely from a non-technical point of view (or at least my attempt at such).

The one thing that occurs to me is that my eye can't figure out what is going on in the image. Is that a door behind the statue? Why is the statue positioned to block the door? Is that even a door? Is the statue sitting on a throne? What is holding the throne up?

In other words, it kind of leaves my eye confused and unable to process the image.

Now for the technical approach...

Your material on Poseidon isn't too bad. A little busy to the eye, but not overly so.

However the material on the lower half of the mermaid is very busy. The material of the walls is very clear and bright, so this sudden change is a bit too much of a change. And to my eye makes the change on the rest of the statues appear to be even more noticeable.

But the metal materials are very nicely done. They look realistically stained and patina for the mermaid and trident. The crown could use a little bit of it too.

Other than that, I think your camera angle might be letting you down. It's almost straight on and I think a bit of an angle would give better depth perception. The angle might make some of the shadows a little more noticeable too, which may resolve some of the lighting issues you think you have.

Although I have to say that it is hard to comment on the lighting without knowing what you are going for. The lighting is very even, which would work for a still life. However, if you wanted more dramatic shadows then I can see why you would think it needed some work.