A lot of the puzzles are really straight forward and good for beginner and intermediate players. What frustrates me the most about the puzzles is that several of the hard puzzles have more than one winning solution; backed by computer analysis. Sometimes you can play a move that absolutely wins, but it’s not the “best” line. Let’s be honest, if one line is +10, and I go with the line that’s +8, they’re both winning. In my mind, a puzzle should only have one “winning” solution. Additionally, there are some puzzles that are mate in x, and you can be wrong if you choose a mating line that takes more moves than the intended solution, i.e., The puzzle may be a mate in 3, but you choose a line that’s mate in 4. It really doesn’t matter. Checkmate is checkmate.
I really like ChessTacticsProPuzzles and have been using it for a long time; I don’t want my frustrations to dismiss that fact. It would beneficial (in my opinion) to introduce alternative correct moves that give the user a chance to find the best solution rather than flat out calling it wrong.