To both 1 and 2, they're definitely good, some of the best titles in the WiiWare store, but it's an acquired taste.

The graphics are all in a very well-done 4-bit throwback style, but what's happening on screen isn't actually a 4-bit game, as there are plenty of special effects, a lot of stuff going on simultaneously, and the music is definitely beyond that of an old Atari. So far, all of these have been rhythm-based games.

Beat has you playing Pong with a zillion particles, all of which hit your paddle in time to the music. Learning the rhythmic patterns is pretty much the only way to memorize where stuff is going, and doing that is the only way to get close to the third stage. It's an awesome exercise in memorization and music cognition.

Then there's Core. The control scheme's easier than Beat since you don't use motion control, just the D-pad and a button. You "zap" particles in four directions to the beat. However, the devs were fully aware that this control scheme is easier to use, so they made it much tougher. I never got past the 2nd boss myself, but then again, I kinda stink at this stuff anyway.

Void I haven't played, but I've seen a lot of footage. It's a lot like the old Flash game Squares - you have particles in two colors on the screen, and you need to collect only one color. The more you collect, the bigger you get, therefore making it easier to collect more particles, but easier to also hit the wrong color and kill you. The particles often appear in a stream coming from one direction, making you navigate a "path" of some sort. There are also some powerups, such as repellent that opens up paths that may trap you. It's rhythm-based like the rest of them.

There's a very arcadey "Don't screw up" feel to it - when you progress without getting hit in these games, you ascend to different levels where your score gets multiplied. However, there are more graphical effects at these levels that are there to distract you just as much as reward you. When you're on death's door, everything goes monochrome and the only sounds you get are beeps out of your controller's sticker, making it easier for you to get back on track.

Seriously, for the low price they go for, they're definitely worth a shot. They get tough, but the experience is pretty awesome if you invest some time in them.

BTW Suiko, nice username and icon! Love that series.