The Basics

You have 7 free spots to place tiles taken from a pile. Once you have added 3 identical tiles they are removed from the game. You can only take tiles from the pile that do not have any tiles on top of them. Each level the pile of tiles is structured in a different way. You get points for levels that are completed within a certain amount of time.

Difficulty

There are a few boosters available, but I have tried to play the game without using them. There seems to be a randomness in how the piles of tiles are generated, and since you cannot always see well what is a below a tile, it is pratically impossible to complete a level on a first try (which you should do, because a second try will give different tiles). I am not completely sure it is possible to complete all fields without boosters. The time factor is a nice addition, allowing you to create your own difficulty (e.g. only aiming to complete a field, or doing so within the allowed time to score 3 stars and a point).

Variation

The different structure of the piles, and randomness of the ways to tiles are arranged in a pile, provides a surprisingly large variation and gives hours of fun.

Visually

The tiles are distinguishable from each other, but what I don't like, whether it is intentionally or not, is that in several levels you will not be able to see which tiles are below another tile, even when the tiles are not completely covering each other. This means you either depend on recalling which tiles are underneath from the initial stacking of the pile (impossible for most), or based on guessing.

Free vs Paid

The game is fully functional for non spenders. The, for these type of game very common, ads are annoying, but can be removed for a small fee. You can also purchase boosters to help you complete the more difficult levels.

Extras

There is a player vs player mode, which might be nice for some, but does not seem too interesting for me. Most importantly it requires two players to play on one device, but the concept of each player taking one tile at a time creates a completely different dynamic of the game that does not seem so interesting to me.
By completing levels within the allowed time you typically also get some rewards, including cards and achievements.

Is It Any Good?

I give Tile Crush 8 out of 10 stars. Some minor flaws will not prevent you from having hours of fun.