I personally prefer smaller maps, there is nothing wrong with getting the Player to go between lots of different maps, it also gives the impression that it is bigger. If I was you I would split up this map to around 4-5 maps, It would then give more of an impression of a deep forest.
Loving the use of the water and the different levels to try and split up, what could have turned out to be a rather boring map, you've done really well