Partners in Time is what a Mario RPG should be like, except for the low difficulty.
The game's graphics where quite good, but not very special, since the DS can do better. The sound is very good, and adds some nice tunes to the game
The good thing of this game is the gameplay. It's an RPG, which is worked out very well. The story leads to some special kind of gameplay, since you get to play with both the older and the younger Mario and Luigi. In the beginning of the game, it's sometimes confusing to use 4 buttons (A, B, X and Y) for the 4 different characters, but after some time you will get used to it.
This is especially fun in the battles. There are turn-based battles where you get experience points to grow in level, but what makes this RPG and other Mario RPG's special, is that you have to do something during the attacks too. When attacking you can increase damage and when defending you can dodge or counter the attack, by pressing the button that matches with the character that is attacking or defending. Special attacking items, 'Bros Items' are strong attack items for which you use this system with two or more characters.
But that is what makes the game too easy. During the game, you get a lot of these attack items, and when you get used to the battle system, it gets very easy to inflict major damage with these items. Both normal and boss battles can be won with the greatest ease, since you'll almost never run out of the items.
Dodging and countering enemy attacks is pretty easy too, as long as you don't press the wrong buttons. Because of this, you don't receive much damage during the battle. And the damage you do get can be easily healed, because you get many healing items during the game.
Outside the battles, the game is easy too. The puzzles in the game are fun, but never really challenging. The most important reason the game outside the battles is easy, is because the second (top) screen, is used to display a map of the area. Because of this, you always know where to go, and because the game itself is very linear too, you will never have a problem finding out where to go.
The other thing the second screen is used for, is to display the babies when you split up. But the other specialty of the DS, the touch screen, is not used in the game. You can't even use it in the menus. There is only one time you have to use it, when you have to wipe something clean. But touch screen functions is not something I need, I even prefer not using the touch screen. But if you look for a touch screen game, you're wrong buying Partners in Time.
The value of the game is not too great, I finished it in 21 hours, but since I'm someone who does everything in the game (battle all enemies etc.), the average gamer will be able to finish it in 15 to 20 hours.
I have played the first Mario & Luigi too, Superstar Saga. And I thought that one was the better one. SSS was easy too, but not as ridiculously easy as PiT. And I also thought SSS had more inspiring levels as PiT, though PiT has good level designs too.
In short, the game has good graphics and sound, and original gameplay. It was a good and fun adventure RPG that was too easy because the battles are too easy since you get many items, and because of the linearity and the display of a level map on the top screen. But the game is not ruined because of this, and the good aspects of the game are more important in my judgement, and that's why my final score is 8.6.