Some consider this game to be the pinnacle of the CW series, me among them. The earlier flaws of the series (come on, you all must have hated that damn get-through-the-shifting-maze-in-9-seconds-or-so part in CW 1 too) are pretty much done away with, and the challenge is quite well balanced. The game also has probably the longest playing time of the series and is also the first to feature player switching, allowing for a huge cast, each with their own special abilities - and making getting the right combination to solve the puzzles an exceptionally sticky wicket.
The plot doesn't figure in as heavily with this installment as in the others, aside from a few encounters as you climb the Alliance Tower. But this isn't much of a flaw; you'll be too damn busy trying to get up to the top to read about the time theorems and evil doings of Mr. C.
The puzzles are, of course, the main part of any CW game. CW9 doesn't skimp on them whatsoever, and the new twist of character selection is added. Although some of the characters really don't do too much (*cough* Asher 2 *cough*), the others have rather a nice variety of skills. And midway through the game, there's an RPG battle where your character selections become rather vital to winning the fight. I personally prefer this fight to the one in CW10 for some reason, I have no clue why.
The graphics don't skimp either. They're all quite amazingly well done, with lots of little blinking and flashing bits and details, and it really looks like a Tower of Technology.
The game's main flaw is that the character selection routine is really, really annoying, since you have to trudge all the way back to the foyer to switch out party members. Chronos fixes this annoyance in CW10, but here, it's still damned bothersome. And you'd better like saving a lot- a lot of the puzzles are amazingly tricky, or are set up so that you won't know it's a puzzle until you walk into it (here I am thinking of the security camera in the prison.) Still, the challenge is a lot more even here than the previous games.
In short, this is the shining gem of the CW series. Download it, or be forever sorrowful and shamed.