Monster Hunter Tri was also my first Monster Hunter game, and I really enjoyed it. In fact I might say that it is too addicting, because I realized after buying it that in 3 weeks I had put more than 60 hours in the game already, and decided to get rid of the game before I became completely addicted.
Pros
Impressive environment visuals
Interesting monsters, it is exciting to get to see a new monster for the first time.
Large amount of customization/weapons/items to master
One of the most impressive online experiences I've had on any console.
Cons
Loading times
Weak story
Slow first few hours
Steep learning curve
Overall 8.8