Portal turned up to 11.
Impossible to play without having a big grin on your face, Portal was revered for being a creative experience with some genuinely funny dialogue. This time around, they've taken what made Portal great and amplified it astronomically. Not only is Portal 2 a ridiculously fun game, it's also overflowing with charm. While you will never see another human being in your time at Aperture Science, you will still meet a few characters that you'll immediately grow fond of. Wheatley, a friendly AI core, stands out from the rest of the small cast. His dialogue is exceptionally well written (as is every other piece of writing in the game), and the delivery from voice actor Stephen Merchant is absolutely superb, nailing small details like hesitation and stammering, and that attention to the small stuff really does make a huge difference in the end. I never thought a sphere could be a great character, but Wheatley is one of the most likeable characters in recent memory, easily. GLaDOS is also masterfully voiced and animated, giving her much more personality than the previous title. As for the third character, it's pretty impressive how amusing someone you never actually interact with can be. That's all I'll say on that.
Of course, behind all of the outstanding writing and presentation lies an exceptional puzzle game. Players from the first game will really appreciate the early romp through some recognizable areas from the first game, and newcomers are quickly taught how to think with portals in the same way the first game did, by introducing a single gameplay mechanic at a time in a natural way, without feeling restrictive. It's done so well that there really isn't a specific place where someone can say "This is where the first real puzzle is".
Everything flows seamlessly onward, and it's pretty crazy that the game can teach you new ways to solve the tests without ever feeling like a tutorial or a chore. Everything just clicks. This impressive feat is made more impressive when you consider all of the new tools you will be working with. Jumppads, laser reflectors, light-bridges, and three gels with unique properties all get thrown into the mix, among other things. The most notable of them are the aforementioned gels. Resembling more of a paint-like substance than a gel, you'll use them to jump higher, run faster, and create more surfaces to place portals on. Some of my favorite tests in the game involve using the bouncy gel and speed gel on ramps to fly insane distances.
I'd be doing a disservice to not mention the sheer scope of the game in comparison to it's predecessor. If you're not sure you'll be getting 60 bucks worth out of this, you should know that the game clocks in at about 8 or 9 hours, and the brilliant writing and puzzle design ensures that none of that time feels padded. On top of the absolutely stellar single player, a surprisingly deep co-op mode is included, with both split screen and online support. It's worth mentioning that there is no matchmaking for the co-op, you'll need to have a friend to invite to your game to play it. That's not really an issue for something like this, though. I don't think anyone wants to play Portal with random strangers.
Portal 2 is a staggering improvement to what was already fantastic. If you haven't picked this up yet, you need to fix that immediately. Buy this game.