gives you slightly more challenging puzzles than in the original game but still not very difficult hence the game being beautifully casual.
Only downside would be that unlike in the original game where music was scarcely used and played only at the right moments to create the best atmospheric experience, in the DLC, however, soundtracks are overused (loop) through the entire stage and thus help you realize even the best music can bore you if repeated too many times.
The DLC is solid but you shouldn't expect it to be out of trend. It can be completed about in an hour or two depending upon how skillful you are. Unless you are willing to support the developers, waiting until it hits 75% discount or higher seems to be a wise choice from a consumer standpoint.