I've gone pretty far into MH3 now, and decided i'd write up what I thought about it, and find out what others thought about it the first time they played.
It's only my second MH game, after MHFU, so I was not sure what to expect. It came as a surprise to start without armour, and I did not like the tutorial part in Moga Woods.
Moga Woods - First off I thought it was nothing special. But, when newer monsters are added, and when your short on supplies, I found it very useful.
D. Island - the quest version of Moga Woods. I thought it was a fill in for the Forest and Hills area.
Sandy Plains - again, I thought it would be a new Desert, but it proved me wrong. No water area, and different navigation through me off...
Flooded Forest - awesome looking area. I reckoned it was a fill in for the Swamp/Jungle, but it's way better. Underwater areas are good there...
Tundra - smallest area in MH3. Only related to the Snowy Mountains by the ice and snow, but no high climbing areas. Haven't done many quests there...
Volcano - epic in comparison to the other Volcanoes i reckon. Has 2 forest areas, but the powderstones pissed me off. They take your health!
Great Jaggi - first fought with full steel armour... got annoyed by his hip check, but otherwise an easy fight. Became even easier with Switch Axe.
Qurupeco - first, I was like "This is gonna fail, MH3's Kut-Ku." It took me down to seconds left the first time. Got pissed and slashed at it randomly with my SnS... then died.
Royal Ludroth - got owned by its roll on land first couple of times, but i found him very predictable underwater. Decent for the first Leviathan boss you actually hunt, and is fun to kill.
Barroth - was not sure what to expect with him. His mud attack still annoys me, but I fought him a lot for his armour and got some tactics down. Really good for an intro to brute wyverns, i reckon.
Gobul - could not be stuffed getting a frog to fish him out with. He was a challenge to begin with, and i got owned by his flash and vacuum... his spike roll is annoying aswell. It's funny carving his antenna though.
Great Baggi - i was expecting a fight much the same as the Great Jaggi's, and i got one, if a little longer. The sleep spit can be annoying, but his attacks aren't very strong.
Lagiacrus (repel) - i prepared for a week to fight him, and got the full Barroth armour. The repel was incredibly easy, and i was lucky. He stayed on land the whole fight!
Rathian - i was excited to fight a monster I had already fought, but with the added attacks. Rathian didn't disappoint, and it was a fun fight, but i hate getting eaten when you have no dung bombs...
Lagiacrus (kill) - was not sure what to expect, i guess i thought it would be like the repel... got owned first time, second time, ate at kitchen then owned him! :D
Rathalos - got Bolt Axe to face this guy. Was pretty tough, lost him a couple of times when he started limping, and his longer time in the air was annoying.
Gigginox - went back and fought him, cos' i thought "What the heck?". Not much of a pseudowyvern, but was very easy and funny to fight.
Barioth - yes, i finally fought Barioth, and... he kicks ass! Got owned by his diving attack a few times, but only fainted once in the quest. EPIC fight, only sucks his Switch Axe is only in upper rank...
Uragaan - I HATE URAGAAN!!! Most of the time I bounce off, and get owned by his roll. I haven't beaten him yet, i'm preparing better weapons. >:( GRRAA!!
Note: I've beaten enough now. Online, nobody in low rank likes fighting him, but he's rather simple. :(
Ceadeus - EPICNESS. His weapons rock, but you need to fight him a couple of times to get them. I don't like his water blast, or current storm, whatever its called... He's also very hard to hit with the dragonator.
Agnaktor - he doesn't come after Ceadeus, but i fought him afterwards anyway. He's pretty hard, but with the right weapon he should be easy. Lost to him first try... Online, his quest is hard to get in low rank, and also hard to get people to help with. In High Rank now, I want his Switch Axe... :D
Deviljho - Only HR 32, but he showed up in my capture Peco quest. Also fought him at a friends house, but they had Alatreon's first LS, and nearly full Jho armour, so it wasn't exactly a challenge... more of an impression when I fight him next ^.^
That's as far as i've got at the moment, not much to go now.