Very nicely written Carl!
I think your post is the most well written I’ve read so far. It’s very nicely structured and super easy to read. It’s also very nice to have the graphs in front of you while reading to accompany your thoughts and descriptions.
You describe the process of playtesting (how you go from feedback in a questionaire to tweaking the game accordingly) very well. It is hard to keep viewing one’s project from the outside looking in, so things like (as you mentioned) bad pick-up sprites might fly by unnoticed. You display very clearly why and how getting external feedback is important and how it affected your game for the better, which is nice.
I actually don’t have any feedback for your post at all, except for maybe resizing the pictures better. They were stretched a bit weirdly.
All in all, very well written post and an interesting read. Hope your game turns out good for release!
Teo's game design blog. 