Not bad for a second game. Far beyond anything I could produce. That being said, keep working on it while I get to play and critique.
Things I liked.
-Fully realized instructions page.
-Credits that reference the music, and if this is a Newgrounds specific upload, a tip of the hat on the Credits & Info links. I really like when I can jump to another artist on Newgrounds without having to hunt for the song that got me queued into them in the first place.
-Upgrades have a visible effect in game. Upgrades also seem to transfer between modes. I don't know for sure simply because of the order that I played the modes. Who plays survival mode without upgrades though? Either way, upgrades transfer, or you get to see what you can upgrade to. yay.
-The length of the game is good for what it is.
-Bombs disappear when you get hit by one. Great for a limited concept of strategy within the game.
Coal in the stocking.
-Some sort of a story, even something as silly as "Santa was outclassing the Luftwaffe at an airshow when things got a little out of hand. Now the reindeer are evading destruction and all those delicious 'thank yous' are going to waste. NOT ON MY WATCH.". That's the story that leaped into my head from the main menu screen anyway.
-Survival mode doesn't seem to have a lot of survival in it. There seems to be the max rate for bomb spawning and that's all. What if you threw in a dependency on collecting the candy canes? Maybe Santa is diabetic, gets fatter, gets slower, ETC.
-I love my mute button. I often have my speakers muted for the reason that I can't mute certain things. Throwing in this simple button though gives the gamer the choice to listen to the provided music, or something that "they" may like better.
-Grindy medals. Yeah I know I "earned" it, but gaining a quantity of something to get a medal just makes me mad. It's a proverbial no skill cookie. How about a score within free mode? Something that takes a thought to get. For example, it seems that as you increase your cookie spawn your candy cane spawn may decrease. This gives the potential for limited replay value without making a person play the same thing over and over. Or a medal for not letting anything dissolve from the ground? Just food for thought.
-No autosave feature means that if you have a computer issue, you better not be grinding something. Having an autosave also means a desire for a clear save though, short of manually clearing history. I think it's okay the way it is for this game though.
-I experienced both of the known bugs that you talk about in the author comments.
-The absolute 0 bomb rate that you talk about also affects survival mode. Sooooooo, go ahead grinders. Get that topscore. Ha.
All in all not bad. Also I am sure that some of the things I listed are planned for your future games. So keep on keeping on, I am excited to see what you do.