Although I think the two Ukulele screenshots look beautiful, I am a bit concerned that they (especially the jungle world) look a bit inorganic. It reminds me of Nuts & Bolts' Nutty Acres, which I really wasn't fond of.
It looks a little like plastic, if that makes sense. And the path, for example, doesn't blend its textures into the grass as we saw in the Banjo games -- the design is very 'clear-cut' and maybe a bit too sharp?
I will have to see how it looks in-game before I can make any real judgement though.