After having travelled in Private Volvos in the south between Bangalore, Hyderabad, Vijayawada and even Mumbai-Bangalore, I travelled in a Volvo in the north last month between Delhi-Manali and Shimla-Delhi.
I have to say that the private transport sector is completely unorganized even in the capital of the country. The private operators are much better in the south and don't cheat the customers too much ( except on the Bangalore-Hyderabad route where the smaller private operators cheat customers a lot ).
Here is my experience of my trip.
Delhi-Manali trip: Booked a ticket from Himachal Volvo tours for the Easter weekend online from Ticketvala. The ticket cost 1200Rs. The bus was supposed to leave from 4:30 PM from Ramakrishna Ashram Marg. At 2PM on the day of travel, I got a call from the operator saying the Volvo bus had a breakdown, so there would be a replacement bus which wouldn't be a volvo bus a Tata Luxuria bus. I had no other option so I said ok.
Since we were starting from Gurgaon, we left early and reached their office by 3:45 PM. Now, the bus that was supposed to start at 4:30 PM did not even arrive till 5:30 PM and the guys were not even bothered about the delay and kept saying they would be starting in another 5 min. Meanwhile I realised that other customers had paid varying amounts for the same bus ticket varying all the way from 900 to 1200 Rs.
Finally the bus started at around 5:35 PM. When we boarded the bus, the helper guy took 10 rs per baggage. I asked them why they were taking this money and he said it was a normal practice here. After arguing why they didnt mention while booking tickets, I let it go ( my problem was not with the money, but why they didn't inform before hand about this charge ). I asked them if they would be charging for giving blankets too and the guy laughed and said no they wouldn't be charging for that ( I didn't realise what he meant till later

).
So finally, after picking up everyone, it was already 8 PM before we left Delhi. I couldn't believe I had left Gurgaon at 2 PM for this bus which was in Delhi till 8 PM. The guys from the travel company got down from the bus and only the driver and the helper were left in the bus. Now, the helper guy gave one water bottle for each 2 seats saying they didn't have enough bottles. I asked him what happens if the 2 people sitting next to each other were not related

and he had no answer. Then when i asked him about the blankets, he said they didn't have any blankets and that he was not liable to answer anything as this bus was just a temporary replacement and they were not related to the travel company with whom we had booked our ticket.
The bus was not comfortable at all and the seats were very bad ( it was not a Volvo afterall) . The driver got lost once and he had turn back after traveling a few kms on the wrong route. After that one of the guys traveling in the bus sat at the front and guided him. The bus was supposed to reach Manali by 9 AM but we reached there by 11:30 AM. There was only one driver for the whole distance which took around 18 hours ( unlike in the south where even the private operators have 2 drivers for any journey more than 8 hours ).
On the return journey from Shimla to Delhi, I had booked my ticket online on the HPTDC Volvo bus. This bus was very good. The seats were very comfortable, everyone got a bottle of water, although no blankets ( I realised that they probably don't give blankets in volvo buses in the north ). The staff was very courteous and the bus started on time and reached before time.
Got my lesson that it is better to travel on the government buses than private buses when you are traveling in the north, while it is the opposite in the South.