The best of its genre !
The interface is as simple as it could be and it's easy to use, it's all we can possibly wish for a point and click adventure game. Clicking on an object/npc you can interact with will bring you a context menu with up to three 'look', 'talk' and 'use' icons. Even if your character April Ryan, the hero of the game, and the npc's are represented in 3D you basically try to move your character in a simulated 3D environment represented in 2D and from time to time, the path finder is a little tricky and it gets then difficult to move your character to a certain spot. It is not an issue as you can just click on the object you want to get close to and April will just walk to there. It becomes an issue when you want her to run to that object. Eventually you will be wanting April to run a lot because her walking speed is so slow it sometimes get boring.
Some of the puzzles or dialogs triggers can get a little tedious some time to time and i had to read the walkthrough once or twice during the adventure but the overall is quite easy and usually you'll progress in the story very easily without even realizing you are even solving any puzzles.
Graphics are old and bad but the art of the game is good enough to makes you forget you're playing a 10 years old game.
The soundtrack of the game can get quite repetitive as you often have to go back-and-forth to places with environmental music but the music is so beautiful that you'll probably find yourself enjoying everything single bit of the soundtrack, half futuristic jazz and half classical ! The voice acting, so vital in this game as almost all dialogs are spoken, is probably the best part of the soundtrack ! It must have asked a tremendous amount of work to put everything together as you can see in the Book of Secrets where you can listen to a good amount of outtakes.
I didn't finish the game yet and i am 25 hours or so into it. Up to now this has been the best story I've ever seen in a game and i have high hopes that the ending will live up to my expectations.
Some point and click adventure games like Terry Pratchett's Discworld or even Monkey Island have a great story and humor but in my opinion fails with unsolvable puzzles. The balance between the puzzle solving, the soundtrack and the visuals in the Longest Journey makes it very immersive and will for sure please every gamer who is in need for an amazing story !