I was really excited to see an art-by-grid app here. This app does, basically, what I hoped it would, however its missing a few key functions to be truly ideal for grid art:
1) It does not allow for an image to be divided into more than 24x16 squares. This is too few squares for large, detailed pieces.
2) It does not feature the ability to number the squares, forcing you to keep track of the current row and column without help.
3) It does not support custom sizing of the grid, so you are stuck with a 3:2 aspect ratio.
4) You cannot edit the image itself in any way apart from its relative size and position on the grid. No cropping/rotation/color controls.
5) The grid lines are more than 1 pixel wide at their thinnest setting. Some fine details may be blocked if the grid overlaps them and can be hard to see even on lower grid transparencies. Too few grid colors as well (only white, black, yellow, and blue).
6) No double-tap zooming, making you use a two-finger-spread to zoom, (making you use both hands, which is not ideal when working on a piece). At its highest level, the zoom fills less than 1/4 of the total screen area with a given square. At some zoom levels, some of the grids lines can disappear from the screen.
Were these issues addressed, I would happily give this app 5 stars. As it stands, its still a recommended purchase, albeit one with some definite shortcomings.