Monster Hunter Tri not only does online play right, but it also gives hundreds of hours of gameplay.
I've never played any of the games in the series before, so getting used to the game was borderline frightening: the game, as I quickly learned, emphasizes trial and error. You have to LEARN about the monsters as you fight them in order to finally take them down. You have to LEARN how and what to combine in order to make new items. You have to LEARN about the different weapons and armors and skills, and what works and what doesn't when mixing and matching them. But that's the beauty of it all--the depth of the game allows you to continue learning well beyond the 100-, 200-, and even 400-hour mark of playing the game.
Instead of talking in-depth about typical review-type things like controls, story, etc., I will point out the major draws of the game. If you're considering the game, then read on! If you're addicted like I am, then there's no need to continue since I am not nit-picking here.
Fighting Monsters--Yes, that's the first big draw of the game. Not only do you get to fight monsters, you get to fight all kinds: including BIG ones. There's no flashy magic to aid you, so you must fight with your own brawn; which, consequently, gives immense satisfaction once you take down a giant beast. And since there are no job classes, you are free to take down monsters any way you choose at any time (more on that later). The thing about these monsters, though, is that they exhibit excellent A.I. Not only will they react to the players in numerous ways, but they will also react to the environment and to EACH OTHER. When you see a Great Jaggi lead a herd of smaller jaggis into battle with a Rathian in the midst of YOUR fight with the Rathian, you will know what I mean. Don't expect giant monster brawls around the clock, though: in order to prevent the monsters from killing each other more than you, they more often than not flee to other parts after damaging each other a little. Except for monsters that help each other. You'll figure it out. :) And the best part? NO HUD FOR THE MONSTERS!! That's right--you'll NEVER see hitpoints, stamina bars, etc. for the monsters. That means you've got to watch them closely and learn how they move when they're hurt or tired!
Playing Online and Offline--I've never played a Wii game with such a seamless online experience. Really, Capcom has done an excellent job of putting together the online experience. Since there are no friend codes to deal with, you can easily meet and add other hunters you meet in the great City (online) so you can find each other later. And four-player hunting is a blast: communicating (via keyboard or Wii-Speak) to take down monsters as they flee (or chase you) a round the environment is extremely gratifying. And don't worry: spoils from playing offline (the Village) and online all go to the same character, so you don't have to worry about "losing time" if your Internet is out (which mine frequently is).
The Spoils--What's the point of MH3, you ask? It's rather simple, yet highly addicting: once you learn how to take down the smallest of the small monsters, you carve them up and combine the materials with other materials you gather from each unique area to make new weapons and armor, or to upgrade existing sets. There are hundreds upon hundreds of unique weapons and armor, which fall into two classes: Blademaster and Bowgunner. Since bowgunners usually stay out of the midst of the fray, they have to wear armor that less-suited to physical attacks. Plus it looks cool. Oh, and if you want to change at any time, you can. Capcom had the foresight to add a "register equipment/bowgun set" feature to your item box to make switching between favorites really easy. You'll see how handy it is when you can do that instead of switching out each armor piece one at a time. Oh, and even though there's no magic, there are elemental properties to weapons and armor--get to know them. And then there's skills. There's lots and lots of skills available, and you can augment the ones already in your armor sets by infusing gems into your armor. Pretty neat, eh?
Dynamic Environments--The last "big draw" in MH3 is the way everything works together in the beautiful locations. Really, without this element, the game would be mediocre. The monsters seem alive in the MH world as they swim, eat, rest, fight, breed, and interact with each other. This really is the most beautiful Wii title I have seen.
There's so much to say about a game that has consumed nearly 450 hours of my life in a scant few months, but I'll won't rant on about it any longer. If you're in the mood for something unique, something always challenging, yet VERY rewarding, then check out Monster Hunter Tri!
(Online play is free in the USA. Don't get confused, because the Japanese have to pay to play.)