1. how's the end game content?
There is some, but it's not as involved as other games that have been out longer. Each major update has been bringing more content for high end players though. The Rift, Helegrod, and Annumis areas are alot of fun and the rewards for getting the appropriate quest items is well worth it IMO.
2. Is there any class who's soloing skill stands out more then others?
This would vary on your playstyle. A minstrel (healer) can solo the same mobs as a champion (dual wielding/offtank)for the most part, but with different methods. A majority of people beleive a Hunter is the best.
3. Is there any class thats hard to get groups for?
No. The only issue with any class not getting a group would be based on how many other types of that class are in it. A group of a Minstrel, Burgalar, and 4 hunters would be chaos. Sure it would work, but not effectively.
4. is there a class that says oh sh*t not another one?
Hunter/Champions are a dime a dozen. This doesnt mean they are not needed, but they are common.
5. and is there a class that is in high demand?
Always always always the Minstrel, and Guardians (main tanks). Each class is balanced well though so no matter what you choose, you will be needed.
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Things I sometimes play...
"What do you want to be when you grow up?"
"I want to be a unicorn!"
"Awww, why's that?"........
"So I can stab people with my face."