Bunches of the same thing is bad, especially bunches of blocking things. Those dirt tiles are extra bad. River should be a little deeper (less shallow tiles), and have less of those rocks in it. Riverbank (grass-to-water edge) should be more randomised (looks too blocky at the moment). Make the cliff.. do.. something (symmetry in geography is rare).
You have the beginning of the right idea with using small mushrooms next to large mushrooms in clusters (on the left of the level), but you've overdone it a bit.
I look forward to seeing a revision of this level and/or new levels from you.
