I'll keep my review short because Shovel Knight is an easy game to review. If you like Duck Tales or Mega Man 2 for the NES, you should buy this game. Period. If this game were released on the NES back in the day and I could have payed $15 to own this game, this may well have been one of my all-time favorite childhood games. I'll spare the time of describing what those game are like (if you haven't played them, you should), so I'll simply comment on what Shovel Knight brings to the table to enhance/detract from the formula that those games nailed. The game mechanics, specifically the Duck Tales "pogo stick" mechanic, are spot-on in terms of feel and consistency of execution. I never felt like I died because the game "cheated" me due to poor controls. The level design is fantastic and the game has a great pace and length - I powered through this in a day as I was having so much fun. I also think the last boss battle is exceptional and is easily better than most, if not all, of the Mega Man bosses.
The only failure of the game is the power-ups (or boss powers if I'm equating to Mega Man 2). The powers you gain from the items you buy (rather than from the boss characters like in Mega Man) are bland and throw-away even though they are clearly modeled after Mega Man boss powers. I was disappointed that I never got the thrill of figuring out that the Wood Shield totally wrecks Air Man from Shovel Knight. While that doesn't take away from the game as the core mechanics are so tight and the power-ups are optional (there is an achievement for not getting any of them while beating the game), this was simply something I expected and didn't get because I know how much obvious Mega Man inspiration is in this game.
The most important thing that this game brings to the table is the soundtrack. While I know this will sound like reviewer hyperbole, I'm going to say it anyway. This is the best top-to-bottom 8 bit soundtrack ever created. Seriously. Better than Mega Man 2. I never thought in my wildest dreams I would ever say that. It is seriously that good. If you need convincing, go listen to it on YouTube. I own the game and I still did because I couldn't get enough of the soundtrack. While everyone will have their favorite tracks just like Mega Man 2 (even though we all know Bubble Man is the best), the sheer quantity and quality of Shovel Knight tracks that you can't get out of your head is a major accomplishment. I also found it particularly cool to learn after the fact that the Mega Man composer wrote a couple of the tracks for Shovel Knight.
I had a blast with Shovel Knight and will probably go back through to play the New Game Plus. I'm really glad to see projects like this still getting made and am more than happy to have paid my money to be part of making sure that we all get a chance to relive and improve upon the old-school genres that I grew up playing.