Being so short, it's hard to get a good feel for it long term. But here are some impressions.
The sounds you picked were pleasing (birds, water rushing), so I enjoyed it on that level. One problem I had, and this might be where some sort of theme music or dialogue might have helped in other games, is that I didn't know where to set my volume. I had it loud enough to hear the birds, but I began to find it a bit irritating after a while (not sure why - somewhat repetitive? and yet not as well. I couldn't tell if it was a single sound or multiple sounds overlapping). When I tried again just now, my volume was a bit lower, and the birds were more background, but then I couldn't hear the water when I changed rooms.
A different reaction: the second time I tried it, I explored a little bit more (to the extent I could), and I found the right-click menu off the birds, once I typed "look at birds". One of the options was "whistle at birds". So I had this:
> whistle to birds
A lyre bird mimics your call!
But as far as I could tell, the sounds didn't reflect that. So it was this odd thing where there were realistic sounds for the background, but I then didn't hear sounds when I did things.
Don't get me wrong - I'm a big fan of sounds in games. I just finished playing Myst V, and not only were the sounds engaging and immersive, but they also occasionally gave additional clues to the puzzles that needed to be solved. But to do have that sense of immersion, they needed to be complete and consistent.
Perhaps you're planning on extending sounds to the actions as well. I'd look forward to trying that out if you do.