This delivers Picross, nothing more, nothing less.
What do you expect from a lighter? Fire? Bring peace to the Middle East? Resolve math problems? There's some things which are simple because they don't need to be any more complexity. Picross Touch is one of those games. It's so simple it's hard to judge. Does it do its job well? It does.
You have Picross which is some one type of game made incredibly easier in electronic formats. You're given clues about which block you need or not to fill and try to resolve the entire puzzle by grouping right clues together. The thrill is that if you get something wrong in the beginning you'll probably carry it until a point of no return. Each move must be made with absolutely zero second-thoughts.
This is what you get here. The environment is stripped-down to basics while puzzle-solving is taken to the extreme. You'll probably never run out of puzzles to solve since it features an ingenuous sharing system that anyone can create a puzzle and send it over. The initial set of puzzles can be completed in a few dozen hours while the rest is there to fulfill any need you might have in the future for Picross.
A while back the game offered up to 25x25 squared puzzles to be solved and submitted. The game came with a set of 5x5, 10x10 and 15x15 originally -- which can be called the base, or main game. Now people can submit not only the 3 original sizes and 20x20 and 25x25, it's possible to create 30x30 and 35x35 puzzles. There's a whole lot already submitted so the meta is made and running. When you try to create a new puzzle the game automatically tries to solve it and if it's impossible you won't be able to send it over. So if its in the system, as hard as it might be, it's still possible -- presuming the computerized system isn't prone to errors, of course, which generally isn't.
This is probably the be-all-end-all of Picross puzzle since it's a pretty basic principle that doesn't really need a whole bunch of graphical extravaganza -- here you can choose the color you wish to see along with the full range of grey shades. Unfortunately it doesn't feature keyboard controls. The mouse works the way it should, you can actually opt for a more complex approach in which pressing the screen will start filling every square it touches while you might think it would become too unwieldy and stay in easy mode where only the specific axis fills squares.
Some options are available to better suit the needs of those more willing to delve into the wonders of Picross but overall the basic principle is the same, click a square with the right button to fill it, click a square with the left click to cross it out. Use the same button to erase any action you which to undo and solve the problems. The only way to make it simpler would be to make it so you could fill squares with the power of the mind.
Picross is as simple as any other kind of paper game, sudoku, crosswords, etc. If you enjoy to pass some time solving these kinds of puzzles you'll have a blast with Picross Touch. The game is free so even if you've never heard of it it's still worth trying it out. If somehow it's not your thing, there's not a single element of this game that would suffice to change your mind. Because there's only one element that needs to be there, and it's Picross.