I feel like the problem with the art is it's too detailed (I feel the same way about AI War, for what it's worth). I think when the art is less granular - like a Super Nintendo game, say - your mind will fill in the details and it'll look fine, but when it's more detailed it just looks a bit jarring.
To bring up an example from the game - I like the art on the world map, for the most part. There are a couple of tiles that are a bit unclear (they look a bit like seaports), but for the most part they're quite evocative in spite of - and, I'd argue, because - of their lower detail.
So I can see a few different potential routes for Arcen, here, for both AVWW and future games:
1. stick to the current art style. It's certainly got its positives, too!
2. switch to a simpler style using lower resolution, more basic sprites. I think this could be a good way to go. Players' minds will fill in the blanks.
3. keep an existing, "busier" art style, but move away from basic sprites as a concept. That could mean simple 3d models, or some other method that lets the art "breathe" more, with range of motion and so on that isn't practical with monolithic sprites alone. As a random example, characters made up of a bunch of different sprites. One example I'm thinking of had a character whose body was a complete sprite other than their right arm, which was a separate sprite to let it animate independently.
Shax, looking over my shoulder, thinks part of the problem is how much of the background is just empty, and how there's a foreground of pretty characters and objects over obviously-tiled backgrounds devoid of detail. I agree with this and I feel like a lot of the areas (I'm thinking of the interiors, here) are lacking in personality; I don't feel a pull to explore them because they often feel pretty samey. I quickly fall into a pattern of wanting to get the items I need and escape as fast as I can.
By contrast, I think the caves can be more interesting and are generally more fun than the interiors.
Caveat to all this that I think the game often looks very nice. A lot of the art is very pretty; it's just the limitations of it that hold it back. Lightning Esper is my pretty monster of the moment.