Do you have any rhythm?
From the get-go, you're given a test to see how rhythmic you are, with some various Japanese text you're unlikely to understand guiding you. It's a slight prelude to the kind of accuracy you're going to need when actually playing the game.
Yes, it's a lot like Warioware to begin with, but each game requires a surprising amount of dedication to complete. You begin starting in the level 1 column with 1 game. The goal of each game within a column is to pass it with at least an "ok" pass. If you do terribly, you'll receiving the "bad" mark at the end. If you complete most of what you need to, you'll get an "ok" mark and be able to go to the next level in the column. Doing it perfectly not only gets you a "great" mark, but you get a medal; one of many.
The literal games are more often then not rhythm based (duh) and can vary from punching flying objects to the beat of the song to stranger things like clapping at the right time during a song performance. Although it mostly ties down to you pressing A or a control pad direction at the right moment, the whole variety of the way the games are presented are likely to make you forget the simple gameplay, especially since the game is so damn charming in every aspect. If you're having problems with some of the more demanding-language-wise levels, the tutorial at the beginning of the stage is likely to help. At the end of a column, you'll be playing a remix. A remix is a collaboration of all the games within the column to ultimately mix up the action and keep you on your toes, while staying true to the song you're playing it to. Some of these songs even have lyrics, which is an excellent addition.
For a rhythm game you need a quite appealing soundtrack. The songs used in Rhythm Tengoku are quite numerous and catchy for the most part. You'll more often then not hum the tunes found in the game not long after you play it, just going to show how much the game grows on you. The sound effects, while abstract, play along to the music so well you'll figure it's part of the song even though the sound wouldn't really appear to fit well.
The visual style of the game is where it scores most of its graphics points, because all things considered the graphics are quite basic and Warioware-esque.
There are tons of toys and minigames to unlock as well for you to tinker with as a distraction, but they come at a price. The medals you get for doing songs very well. This is where a lot of the value comes from. The challenge and persistence to get these medals, even though the slightest mistake in beat detection can be the death of a perfect score.
If I had to find a drawback, it would probably be that some of the games aren't quite up to par with some others, usually relating to the chore-like gameplay of a few special cases (ie the game show one) or just plain too difficult to do well on (ie the rabbit jumping one).
Rhythm Tengoku still shines despite it's simple gameplay and frustrating moments, and provides a quite smile-inducing experience you're not likely to forget. Especially not with the game music playing in your head all day.