It depends on what kind of game you like:
If you like arcade games, with little action, or games the are more of a puzzle, then I suggest you download it. It is very similar to Candy Crush, however you can catch the Pokemon, so from what I have seen or heard, it is more fun. The game is free to download, so in that regard it doesn't really matter, as you can just not playing it if you get bored.
If you like action games, such as the main series Pokemon games, I would suggest NOT to get it. If you don't like puzzle games, it will just be a waste of time, and you could be using that time to play other games that are more to your liking.
(Thanks to Astronautical for mentioning that Pokemon Shuffle is free to download :P)
Personally, I would download it. Its free, so there's nothing to lose. You can play it to pass the time, and if you were to get bored, you can just leave it.