Whilst not a rule of thumb, free iPhone games are usually free because they’re rubbish. Depict is the reason why there isn’t a rule of thumb.
The object of the game is simple: it’s online charades. One player is given an item to draw, and the other players are given multiple choice answers. The points you’re awarded relies solely on the order in which you guessed correctly. If you continually guess the quickest, you’ll win the game. If you’re too slow, you may end up with very few, or no points at all. The iPhone’s touch screen is almost perfect for this type of game (I’m going to go out on a limb and say this would be far more suited to the iPad) and the title works over WiFi and cellular data, so you can play a quick game wherever you are. And for the cheaters of the world, there’s a report function when someone doesn’t actually draw the item in question, but writes its name down.
I’ve seen far worse games being sold on the iTunes Store, and Makeshift Games could’ve easily got away with selling Depict for a small sum. But considering it’s free, there’s no harm in downloading it as a good timewaster.