Thank you @Anonnymitet, you make some very good observations.
1. I am planning on an intro and scene setting level which will also introduce the controls.
2. I know what you mean about the gravity. The other side of the coin is I don't want the player's movement to appear too arcade like - quick jumps and falls - I want it to be watchable, if that makes sense. I will have a play around, though, and see if I can tweak it to be better.
3. You're one step ahead of me and the point is completely valid - the demo of level 2 (a few weeks away I think) will show a new fall animation. Hard to get perfect and I suspect it will get adjusted a few times still... But it looks more realistic than the upright jump the current demo shows.
4. I agree! The piranhas were supposed to be a bit of fun, but the transition to a full skeleton is too quick and doesn't do justice to the atmosphere I'm trying to create. Pity - it took me quite a while to set up....
I really appreciate the feedback and hope you'll check keep an eye on things here as I slowly progress (around my day job)