Thank you for your responses. I think these additions give more meaning to a biome. For instance the moss, I think will help with Thaumcraft research.
There are more things, too. For example, Jungle biomes have new spawns; Jungle Spiders. They are smaller and faster and tend to run in packs. They're like the mine spiders but I don't recall them being poisonous.
In general BoP adds a ton of stuff and works pretty well with Natura.