That would work if he wanted to change it to a u-shaped, but I think the "island on the left" is a find lay out. My suggestions are going to be based on this lay out, but can be applied to a u-shape as well.
There are 2 things that immediately come to mind when looking at this tank:
--The naked wood takes too much attention
--The mid-ground is weak.
The first problem is the more blatant one-- without any plants on it, the wood's warm color completely takes attention away from the plants. Planting ferns and anubias on the wood will fix this problem; especially anubias, whose dark green will help to integrate the wood with the rest of the piece, and make the viewer draw more attention to the more brightly colored plants. Leave some of the wood bear-- your goals are to reach integration, while creating more contrasting elements. Right now the wood seems completely out of place.
note: When people talk about plants to tie to wood, they normally say, anubias, ferns, and moss. However, it's been my experience that moss and riccia usually do not look good together in the same tank. Not sure why-- maybe it's because they look too similar with different colors, but for whatever the reason it doesn't work for most tanks.
The second problem hurts the depth of the tank. With a sheer change from tiny glosso to tall stem plants, we get th impression of looking inside a box. Yes it is a box but that's not the feel we want to portray. It makes us feel like the aquarium is tiny, and is flat. Some thick mid-ground growth is needed to add depth and flow, creating a "large picture in a small space." Anubias would also make a good mid-ground plant in this tank, planted in front of the wood, especially if it is also planted on the wood. Make sure rhizomes are not buried. I recommend anubias nana for both purposes. You could go with crypts, but a brown crypt will create the exact same problem as the naked wood. Try to find an olive-green crypt if you are going to use one. Hemianthus micranthemoides is another popular mid-ground plant, and a personal favorite of mine. This plant would create a lighter feel, and its similar color to glosso makes the two compliment each other well. However, make sure you have enough dark green. You don't want every part of the tank screaming for attention-- you want enough dark colored plants to support the bright fore and backgrounds.
The microswords planted on the right side behind the glosso make the tank look flat since they're planted in a neat line up against the glass. Looks very unnatural- like a picket fence. I would start by taking out the two bunches of the microswords furthest to the right. Re-plant most of them in front of the others, so the swords look thicker and can help support the mid-ground to the right of the island.
Now, why did I say "replant most?" I wanted you to save some to use as highlight plants. High light plants are slightly taller plants scattered amongst the foreground. This gives the foreground greater variety, making it look more natural, and makes it look like it has greater depth. A beautiful field has a primary type of grass, and then weeds scattered amongst it. That's what we're doing here. You can create this by carefully planting individual grass plantlets in different places amongst the glosso.
Or you could make all the grass plantlets high-lights in the glosso, and then plant some other mid-ground plant back there, like hemianthus micranthemoides-- which would be good there as it would finish the slope of brightly colored stem plants.
Those are my suggestions for now, good luck!