Hi amso4,
First of all, welcome to APC, I see this is your first post. Lots of good information and helpful supportive people here to help each other learn and enjoy this interesting hobby even more.
I like your tank. That said, I agree with Chester that sloping the substrate would help add visual depth. Also having keeping plant varieties together in groupings helps to add mass and using plants with different leaf textures and colors interest and impact. Keep up the good work!