Personally I found it very enjoyable. I was particularly enamoured with the pixel graphics, I felt they gave the game that classic old-school shooter look whilst still being very well drawn and beautifully presented. It's a tiny bit rough around the edges at the moment but nothing I wouldn't expect from a pre-release, I'm sure there's nothing I can point out that you're not already aware of and planning to address before the full release. I have to say I'm really looking forward to it and can't wait to see what the new content brings!
The only slightly odd thing (which is nothing to do with the game itself) is why there was no mention on the giveaway page that this is a pre-release demo rather than the full game. It's usually made very clear what a giveaway actually comprises of but there wasn't even the slightest hint that this is a demo of a currently unreleased game. Still, that's got nothing to do with the game which I think is great! Certainly one I'll be keeping my eye on, if the price is right I'll definitely be picking up the finished product!
Thanks for your efforts, cheers!