Unfortunately, the dated gameplay mechanics, weak stories and dire music hinder the game immensly.
The gameplay is phenomenally old fashioned and it will grate some people because it's not as accessible as say, Broken Sword or Grim Fandango. It does grate that you have to keep clicking an action icon e.g. pick up; talk to; examine; move etc and then click the item or object. It slows the pace down a little bit and gets frustrating when you keep doing the same action because you keep pressing A to forward the manoeuvre, thus looping the action! Also, the game has a fantastically steep learning curve for casual gamers simply because there's no real indication on what to do next. You wander around aimlessly, clicking and trying absolutely everything in finding out what to do next. Sometimes you can miss certain items or events simply because it's not highlighted or blends too much into the background. Another gripe I have is the horrendous dead ends you will encounter simply because your curiosity and frustration gets the better of you. For example, early on in the game when you leave the restaurant, you're free to explore the streets. If you approach the police station and then turn left you fall down a manhole opening and die. It's badly out of date and is unashamedly unfair. This game severely relies on constant back tracking and trial and error; it just hinders the pace and damages the game. The puzzles are obscure or confusing; just wait until you try the second game, which is even more frustrating and confusing.
Ah yes, the graphical limitations of the Game Boy Color must always be taken into consideration when dealing with its games. Deja Vu 1 and 2 makes exceptional use of its limitations and is a fine looking game. The game is almost devoid of any animations and each background is static. It's not bad, considering it's a GBC game.
The sound is truly awful in this game. The sound effects are okay but the music quickly grates and annoys you. It's far too high pitched and is really, really out dated. I had to play this game with the volume turned down because I couldn't take the music any more. Making good music on the Game Boy can be done. Listen to Pokemon, Metal Gear Solid or Lemmings for shining examples. Deja Vu is unfortunately, a horrible game to listen too.
The game is really short. Both casebooks will take you ten hours or less to complete both and believe me, there's absolutely no reason as to why you would want to play it all again. Deja Vu 1 and 2 is a weak game because it's out dated and is just not an appropriate game for on the go playing. The stories are okay but are affected by the horrible, old controls and even if the controls were improved the story still wouldn't be good. For nostalgia purposes, give the game a try but thank your lucky stars that Lucas Arts, Revolution and Sierra evolved the point click and genre and made it accessible. The game's flaw is it's outdated feel to it, it's not intuitive and it lacks a really good story.