Today's update adds 34 achievements to Puzzle Together. All achievements that can be earned are listed on the Guide page, and the achievements you've gained are listed under Stats (as well as in Steam).
Several of the achievements are fairly easy to earn, while others are fiendishly tricky or require epic amounts of puzzling! Long time players needn't worry, you will be credited for achievements already earned before this update, once you complete your next puzzle.
Of the 34 achievements, 19 of the more difficult ones come with one or more free puzzle credits when earned, that you can use to unlock any puzzles of your choosing.