I've only played POE for a few hours so far, and I'm playing on the hard difficulty setting.
And I must say when my party was killed quite easily on around my 4 or 5 encounter, I felt happy.
Because I thought "This game is going to require me to think about my combat strategy"
After this I began to work at this strategy using the characters in separate ways, and moving them around separately into different positions.
Where as if I was to run in with all my characters to attack say 3 Wolf's then really it's a good thing when they all get knocked out.
If they killed the 3 Wolf's quite easily... Well that's not challenge, it would be too easy.
So, so far I'm finding it fun, enjoyable, and challenging to learn about and find different methods that work in combat.
Sneaking with one character is easy btw.. I'm not sure why people are having an issue with that.