Imagine this as a limited-time free app: you can play it through its thirty puzzles, and then it kind of becomes useless, unless you enjoy re-doing the same crossword puzzle. It is intended as a way to whet your appetite and get you to buy the paid app. Fair enough, no problem there--just be aware of the limitations.
The puzzles are definitely not NYT difficulty, but for me that works fine--at my level (relative novice), the puzzles are hard enough to challenge me, but not so easy as to make it worthless (YMMV). The design is OK, but there are a few small glitches or flaws. When you rotate, the animation freezes for a moment in mid-rotate (at least on my machine); not a biggie, but it does get annoying, as you have to rotate it a lot. In portrait mode, you can get hints, info, and clues, but I don't see an easy way to switch from horizontal to vertical. In landscape mode, you can switch between horizontal and vertical, but you can't get info, clues, or hints. So if you want any combinations, you gotta rotate fairly often.
Other than that, it's great. The keyboard is easy to use, and the puzzle squares surprisingly easy to select. There are a few more features I'd probably want to ask for if I bought the main version, but nothing that would stop me from buying CrosswordLight , really. I'm just not *that* big a crossword fan.