I've written about how great Monument Valley is previously. Now there is an expansion that adds eight more levels that fit nicely right before the last level in the original game. This expansion can be finished quite quickly, but it is totally worth the extra $2.49.
There are new features added to how puzzles work in this expansion. You can twist geometry now, there is definitely more impossible geometry, rooms change completely when you turn them, there is lots of upside-down action. Sometimes it's easier to hold your iPad upside-down to complete a level, it's quite fun with all the twisting and turning!
The order that the levels have to be completed is not set. You have to do the first level first, but then levels 2-7 can be done in any order you choose. Once all of the levels up to 7 are completed, level 8 is unlocked.
Level 8, the final level takes a lot more effort to finish than the rest, but once you figure out what needs to be done it's easy and very linear. Whereas the ending in the original was quite a sight, the expansion is let down in this respect. However, when you do finish level 8, there is quite an awesome lead in to the original game's final level.
Here are some screenshots.