[Note: There's also a video review!]
Bit.Trip Core's structure and goal are the same as Beat's: Pixels fly at you; you zap them; and it plays a tune for each successful zapping. It's all still a fantastical, colorful experience, but it's thankfully easier to play due to a more simplified control scheme than the unresponsive motion-based ones in Beat, which had you tilting the Wiimote to move around.
In Core, it's very different; a d-pad resides in the middle of the screen and by pressing a certain direction, you'll shine a beam of light that way. As you start zapping pixels in succession, you'll fill up a gauge that lets you perform a screen-clearing move. The game benefits greatly from this control scheme, as it's more reliable than the motion-based tomfoolery that went on with Bit.Trip Beat.
That's not to say the game is simple, by any means. Pixels fly at you at punishing speed and zapping the majority of them is a daunting task. It's an almost instant shift too, where you're playing a nice, serene bit of a level only to all of a sudden be hammered with walls of pixels. The difficulty spikes are an obstacle and if you're an easily-frustrated gamer, this is going to bring out your worst. But, for me, the new controls kept me playing longer than I did in Beat.
If you enjoyed its predecessor, then there isn't going to be anything in Core you won't like. It's got a way more comfortable controls and the charmingly retro Bit.Trip approach remains a unique twist on the music genre.