I'm a Monster Hunter vet from the games on the PSP. I never really got much further in the "G-rank/master" quests back then.
I consider myself an intermediate gamer (not casual, not hardcore), and from experience Iceborne has it's good and bad. I have over 1200 hours (split between 2 characters) and use a wide variety of weapons.
The Good: Increase in the monster roster, a new habitat (maybe more in the future) to explore, new gameplay mechanics with the clutch claw addition.
The Bad: The clutch claw is great but somewhat badly implemented for the difficulty increase. Good luck trying to use it at all on monsters that are 99% enraged the entire fight. You might be able to weaken/drop ammo with the clutch (certain weapons end up being so random with the clutch claw results you have to attempt to use it twice for two separate results while other weapons only have to use it ONCE).
Certain monsters and situations will make the fights drag out unnecessarily long due to things like dung pods or other basic game mechanics becoming ineffective (even from the start of a quest) for long periods of time during a fight. Tip: If a monster is airborne there are 3 ways to bring it down. Flash bombs (which build temporary immunity to if over used), Clutch claw burst to the head (if not enraged or BS immunity just because), and status effects (mostly ranged weapons) like sleep/paralysis.
If one is new to the Monster Hunter series with World, expect a very sharp increase in difficulty with certain monsters in Iceborne. Also if one has been paying attention to the mass of tutorials for new comers, a lot of the skills you can use with armor sets can sometimes become quite impaired.
Windows of opportunity have been decreased to the point where players can spend a good 80%+ of the fight being dragged out unnecessarily because of lack of opportunity to do ANYTHING but run away or try to avoid being hit. (Hello farcaster...) The AI will become cheesy to fight, and players have to cheese to win. It usually takes 4~6seconds for a player to use any SINGLE item (excluding mantles) without skills to reduce that time. The monsters can do about 3+ attacks within that time frame and you're at a severe disadvantage if you're trying to heal, then sharpen your weapon, then drink buff potions etc.
If you're a casual gamer who just wants extra monsters to fight, but not willing to invest the time to pad out your armory (both a variety of weapons and armor sets) for you will probably not be able to enjoy the expansion because it shows that knowing what to do and having the right equipment matters a lot. Tip: Learn at least 2 different melee weapons and one ranged weapon. What may be harder to take down with one weapon may be easier with another.
I still see vet players with equal amounts of "experience" still running around with wrong element/status effect weapons that monsters are strong against, or being affected by things like tremor/roars/defense down and carting the missions due to lack of having enough defensive skills on their armor and aiming for attack only. DPS matters only when you can actually not be stun locked or carted a majority of the time.
If you're a masochistic "hardcore" gamer who loves running into walls all the time you'll find some monsters in Iceborne that will float your boat. If you're an experienced gamer who likes a challenge but not insane difficulty you'll still find some decently balanced fights in the game. If you're a casual gamer that doesn't want to do too much, but are willing to take the time to get better... be prepared for some hellish treatment. Anyone below that probably won't like it.