Monster Hunter 2 Dos is a total new structure from the other PS2 versions, mainly due to the new weapons and environments. There are a LOT more monsters to deal with and more items to claim! New innovative features such as night and day effect the type of monsters and items appear, same for the seasons. You will be spending a good amount of time on the first stage, gathering materials for your armour and weapons. More so than the other two PS2 versions. Though, the cost for the armor and weapons have gone down and the amount you get paid for each quest is sufficient enough for you to keep on saving and not worrying about what to spend your money on.
The newly added monsters aren't much of a problem as the rest that you have dealt with before, all you need to do is keep in mind of how they attack. For example when you face the baboons in the jungle area, make sure to not stand behind them when they fart. Yes, they fart and it will hurt you plus you can NOT use any edible items. Fun times... The amount of enemies on screen is not too much for one person to take care, that is until a huge wyvern stomps on in. That is something I will address later on. As for the new weapons, well I leave the choices up to you. You have now a Gun Lance, a hybrid flute/hammer weapon called the Hunting Horn, Bow & Arrow, and katanas. All have their own set of controls and use in battle. For example, the Gun Lance can be used for mid range attacks and close combat. And the Hunting Horn weapon for raising party stats and smack enemies around. There is however one BIG difference in a set of weapons that I have noticed. The Sword & Shield has a lot more "umph" or power this time around. In the previous two versions, the S&S has gotten little amounts of love due to it's attack power and range. Not anymore, well the range is the same but the status effects make a big difference. And with the Dual Swords and S&S, you can use your item WHILE they are drawn out. Nice.
Right now, I'm using the Death Prize and it has a Stun attack that will keep almost any monster/wyvern in check. Same goes for the Hammers, since they have a higher success rate in inflicting Elemental damage. The Bow & Arrow is pretty good with the pierce attacks and status infliction also. So far, most weapons are balanced out for the player to try out and get comfortable with.
Now, I can't get the issues that have been stuck in my mind since I bought the game, out. The first and most important one is this; Why the hell aren't the other monsters leaving the area when a big and nasty wyvern comes on screen? They do in the videos, but not in the game. When I'm fighting a Rathalos, I have to deal with those Velociprey also! They should be running away scared because of the presence of such a great beast and the fact that I killed more than half of them to begin with. It's like the A.I. has not been fixed and makes the game play much more annoying. Want some realism? Have those smaller monsters run in fear and let us hunters deal with the wyvern.
And another issue is the hit box for the player. Example is when I'm close to the left side of the Zazami (large crab boss), he does his water attack and I get hit by his claw even though I'm not in direct contact with it. Same goes for any of those raptor creatures that attack you. It's problem that will hopefully be fixed in any of the later titles.
The last issue is the usage of items in battle. Now I understand it's stupid to sharpen your weapon while being in front of a boss or any other monster, but when you're running away from a wyvern on the same map area and you need to restore some health. No way, dude. Right when you use that drink, you can not move while your character is doing is animation. Which should be cancelled at the time the player needs to move away from a boss or monster attack. I remember laying down a stun trap for the Kut Ku and it flew away, but I was still in the process of laying it down and it was my only one. Why can't I cancel that? I wanted to stop the animation of myself setting the trap that the loss of a useful item that would have gone to waste. Nope. Once you use that item, there is no going back. Again, another issue that needs to be fixed.
If you're a fan of the series, then by all means go and import it. It has better game play and new features to gawk at. But there is still that question on why hasn't this game been released over here? I'd like to say more, but I think it'd be best to hear from the source itself.

The third generation of Monster Hunter drags the series back to western shores because well, why not? In fact you could say that three really has been the magic number. Unless you live in Japan in which case one and two were also pretty fantastic and if anything three has been nothing short of a crushing disappointment.
‘But wait!’ Voletic hears you scream, ‘Monster Hunter 4 Ultimate has been recently announced, why are you addressing the third iteration?’ Because background knowledge is a beautiful thing and Voletic has a word count to fill.
My problem with MH is the slow paced and plain combat system, if they make it more dynamic count me in.
They need a full console release, launch the CryEngine one for PC for PS4/XO. And make sure to bring it stateside.

In an internally conducted interview at Capcom, Monster Hunter series director Kaname Fujioka recently touched upon different aspects of the franchise, its growth in Japan, its Western audience, and how it has evolved over the years. In one of the questions, Fujioka is asked which Monster Hunter left the biggest impression on him.

"Greetings fellow monster hunters! It’s always nice to see new faces around the guild hall! So you’re wanting to learn how to hunt monsters? Well you’ve come to the right place, young ones! Let me pass on my tips and tricks that came from countless hunts for the big and the small!" - Declan McGeachey of Geekenstein.com