The puzzle concept is fun, but it's been around in puzzle magazines for centuries. This wouldn't be a problem if this was a computer port that did away with the constraints of solving these puzzles with pen and paper, such as having to check the answers manually, having to painstakingly draw X's and O's in squares, and all that, but somehow this game made it even more uncomfortable than simply getting the puzzle in print and solving it.
I'll start by saying that this interface is horrible. You shouldn't have to drag and drop X's and O's. This is an electronic game, you know, you could have made it so that we can simply click a cell in order to mark it.
Second, why the hell do I have to check the solution myself? Once again, this is an electronic game, it should be able to verify the solution by itself. The worst part is that there's no "back" button to re-check my own answer after I clicked "check answer", and that's even worse than pen and paper, since you can at least turn back to the page containing the original puzzle after checking the solution page.
I feel like I'm playing a magazine puzzle printed on a fridge using fridge magnets in this game. If you're going to port a pen-and-paper game to an electronic game, do away with the physical constraints of pen and paper rather than making them worse, geez.
The single puzzle presented in the game is not bad, but there's only exactly one puzzle. So, the game is too short.
Now that I look at it, this game was released all the way back in 2002. If it were released nowadays, no way it would be rated three stars. Strange how browser game standards have raised in recent years.