We had the big blue or black background discussion back when I was setting my latest 30 gallon up, and it was pretty evenly split for opinions. I finally opted for the blue, and I think it looks great. I think it's mostly a matter of personal taste.
About the only thing I'd do differently is move the Angel to a bigger tank, and put a few smaller schooling fish in there.
I think that some of the plants are too big or too maintenance intenisive for that size tank:
Hygrophilla angustifolia - if it grows well it will have to be trimmed pretty seriously every week leaving the plant not that nice looking as it is on the picture.
The banana plant - don't know the Latin name - that plant loves to shoot floating leaves and if conditions are good it will start to produce bigger leaves first and probably look crowded. The floating leaves come later and are about 3+ inches in diameter - will block some of the light.
The sword - I'm not sure that is a sword but it looks like it to me. Some of them look cute & sweet when little but they turn into huge monsters in 2 weeks if conditions suit them.
My opinion is to keep the smaller plants or remove some plants so the tank doesn't look crowded. It looks like a nice and clean tank!
First I should say that this tank has been set up for a a year and a half now, but has gone through 3-5 different aquascapes during this time period. I have found this one to be the best so far.
Jan... The Angel has been in the tank almost as long as the tank has been set up, she does just fine and lays eggs on occasion. However I do plan on moving her to my 55G in the near future (this summer). On the background, I do plan on going with a darker blue but just have never got around to doing that.
Niko... The Hygro I moved over from some trimmings in my 55G, so I'm aware of how big it gets; it's just temporary until I find a replacement plant. The Banana plant has been in the tank since day one. The most floating leaves I have had at one time is 5-6 at the most (1 now). I have not found that they block enough light to matter, if that becomes a problem I will just clip them off. I do have a Amazon sword & two melon swords, the melons have not taken off yet and the Amazon (also a transfer from the 55G tank) I keep the leaves pruned.