4 stars: Good game, but button layout is mediocre. Every time I've used a hint and the majority of my mistakes are because of mistaps. The number buttons are too close together and the hunt button is easy to accidentally tap on the way back to a rest position. If you're left handed you'll have less issues. The ads aren't too intrusive, but I wish they'd filter some out. Some are double and triple close ads with false x buttons.
4 stars: This is an update to previous review. The have designed well and standing system is fair. Only issue with me are loud adds, with pop up windows (new Google play Windows with backup window ad playing looks music) so I complained and company promised to look into it. Originally all adds had a small mute control... Was acceptable as balance.
3 stars: Stacked ads - painful. The game itself is a good version of sudoku, but the ads...my god the ads...more and more and more. Seems like every single click now results in an ad. I hate the fact that some ads now hang...and force you to Google play. Uninstalled
3 stars: Would give higher but too many ads. Have to watch even when you hit skip it forces at least another 5 seconds. Also plays 2 ads between games, one when you finish a game and another before you can start the next game. Then if you pause you have to watch another ad.
4 stars: Not at all bad. Could do without that autocomplete thingy. Apart from that, definitely playable. Hope it gets harder though (hence the 4* - a bit easy ...