Actually Opop,it looks worse than it is. If you approach it with the right attitude the Leh- Manali route is amazing. I left Leh at about 1am by share jeep RS1200 for front seat & i had already been awake since 8am the previous morning. I did the "rocket run" which took around 16hrs to Manali & loved every second of it, the state of the roads & the switchbacks & the vast spaces of emptiness & the distant snow covered peaks in the distance as you head for the passes don't give you time to think "I am bored how much longer now? or my body is aching with all this bouncing around when will it end?" In fact when i arrived in Manali late that afternoon i was buzzing with energy it felt like i was on a natural high (either that or i'd just been awake for too long!)
I've done the Manali- Dharamsala journey 4 times now & the scenery is quiet the reverse from the Leh run, but just as enjoyable, the buses ain't that bad, however a days break in Mandi would definitely make the experience more enjoyable.

KK