Im doing one good playthrough (not even finished yet), but I plan on doing some badass assasin breton type character for all the fun evil stuff, but im wondering.

Is good v bad a whole different game?

I mean, so far ive spent very little time sneaking, or murdering or being arrested or anything. Mostly killing bandits and beasts. I assume the criminal element really becomes a big deal and a different game once I restart for the evil playthrough?!

Without spoiling, could people please tell me if I should be looking forward to a brand new 50% of skyrim I have yet to see?

Well you'll obviously have some new questlines, and the playstyle is entirely different.

its not a 'whole new thing' like say in a game like KOTOR , its what you make of it , which can be quite a lot if you go round stealing and murdering. It might just be in my head but it feels a lot diffrent to me.

I started my "kill and steal everything" character a couple days ago. It is certainly different.

There are hired thugs after me before I've even left the first town and heading to whiterun is suicide since all the guards are already after me. I'm forced to find new ways to get what I need. I've spent a LOT of time in the wilderness. I also play at master difficulty.

Try it. It's different. You'll enjoy the challenge. Go all out.

I plan on going thieves, assasins, vampire and whatever else evil I can do.

*spoilers*

Werewolves were for my first good playthrough, was not expecting it! Hahaha.