I think most people will be disappointed at Polarium, and I recommend a try before your buy. The puzzle mode will last maybe a couple fo nights- consider the puzzle at your disposal - a board of black and white squares, and having to flip them so horizontal lines are the same colour, with the idea that those you flip must be in one continual stroke. If you're reasonably good at logical thinking, the puzzle solutions become obvious,a s there are certain things you cannot do in this mode to solve the puzzle (example: Horizontally adjacent blocks that are different colours means your stroke cannot go across them).
As for the Challenge mode, it's fairly brutal, but as many have said before it's not random. The first 100 lines consist of a series of triple row blocks of set pattern (like a mostly black with a couple of white vertical strips) falling until 100 is reached, then level 2 comes, which is mostly a series of one row blocks with intermittent white spots. Level 3then becomes a series of 3-4 row blocks wiht a symmetrical pattern.... and so on and so forth. Each level (each set of 100 lines) has a particular way of clearing it, and the supposed 'challenge' is figuring that out. But once you do, it's simply going through the motions. That is, start a new challenge mode, and you're simply playing level 1,2, or anyof the ones you've mastered to get to the new one (there is a practice mode that lets you select any level you've reached to practice it) - ie boring.
Now, of course, there're a number of strategies to clearing the lines. You can take them one set of rows at a time, clearing them as each falls, or waiting for a number of them to fall, flipping certain blocks to setup a larger combo to clear more lines, to get higher score. However, it seems the biggest points bonus comes from clearing a screen at any one moment - so a combination of strategies is the best. Early levels allow this, but later levels it just becomes a slog of clearing a few lines a time. Try to imagine playing tetris where you don't really have the choice of how to clear lines at any one time, not becasue the game doesn't let you, but because it simply isn't a good strategy in that level.
On top of that, the controls can leave a bit to be desired -the stylus can be less than responsive and precise, adn for a game like this, it can make or break it. The calibration on your stylus has to be perfect, and by my experience, the calibration for this game is not the same as my others (dead centre for the stylus in pictochat means a slelction point 4-5 pixels off the touch point in polarium). I can only hope this isn't a consequence of this control style in future games, requiring me to calibrate for every game - or at least build a calibration system for each game (I really don't know how touch screen input functions or is programmed).
Top off with the fact that these are the ONLY two modes for a single player. Puzzle (admittedly with a design your own puzzles -but I can't see how compelling that can be on your own), and challenge, which appears to more a memorisation feat than anything else.
Of course, this change had you more people to play with: Maybe when it comes out, people here can come out with puzzles and post them on the forum and challenge people to finish them, creating a GAF polarium community.
But as its own game, I probably only give it a 5.