With my current character I'm about 65 hrs in and still haven't aquired a mount. The reason being that I heard that horses attack every bloody thing in sight, like Shadowmere did in OB. The only stable I've been to so far is in Whiterun and that horse looks crazy plus the seller implied as much. Do all horses in the game behave the same or are there some that are less aggressive and if so where can I get one?

Anyone?

They're not a crazy as they are plain useless. Walking doesn't take that long, and you can get to any town you haven't been to yet for less than 50 gold from the carriage man. I had a horse, never used him after the first 3 or 4 trips, and then one time after a fast travel, he spawned next to me and my follower as a corpse. Must have run off to attack a mammoth or something and I didn't notice before fast traveling. I was actually glad he was dead.

Where did you aquire that horse?

They tend to help you with easy enemies and run away when enemies are more challenging, to me they seem to work right in that regard.

It's the one they sell at Whiterun for 1000 gold. The black one.

I am at over 80 hours and have not bought a horse yet. The only use I can think for them would be for exploring only.

I have the one from Whiterun and, he attacks everything including Dragons. He was actually better at defeating enemies than the dog.
He never really got hurt until after the 1.2 bugpatch. Now one wolf bite, and he's dead.