besides others, i played now a while as a thief/mage combo which gets quite challenging (especially when youre lacking the perks to do more sneak damage)...a destruction spell on one hand often helps to aim at certain weaknesses but with light armor and a lot of enemies being extremely strong...im going down fast...you feel the lack of armor and shield in direct combats which you can not always avoid (especially during boss battles or when several chaurus attack at once)...what works often well is archery - on human enemies...on stronger beasts (chaurus, falmer)...things get tricky...
i also found out that due to the very steep increase in "magicka" costs for spells, its porbably hard to use a lot of spell schools at the same time...spreading out your character on a lot of skills seems difficult which i now realise...pure thief is also very challenging if you cant silently kill cause in direct combat without armor or magic aid.... havent tried a pure caster yet but i assume its very tough until you have enough spells/utility and magicka....
from my experience:
thief/thieflike gameplay starts the easiest but gets difficult very fast (maybe it gets easier again once you get most of the damage sneak skills)
daggers are useless if you dont have the sneak 15x dam skill...
bows are very useful to sneak kill...because you often can hide again and kill so even tougher enemies
focussing on few magic schools works better cause youll soon run out of magicka if you dont get the 50% perks...
destruction spells often help to combat single foes cause you can burn em to crisp while they are staggered from a powerattack or charging you (while a shield often staggers you when your being hit, at least in the beginning if you cant time a bash properly)
what have you learned so far? enjoyed?