in my opinion, the bus tour does cover the periphery of the tourist attractions and provides a good way to get oriented to the cities layout, it does not cover the heart of the attractions in the main tourist area. These are best covered by walking the core tourist area. The bus ride itself is bumpy but that is due as much to the streets as the quality of the bus suspension. Taking pictures from the bus is a challenge. Because most of the attractions are in the central core the best way to enjoy Naples is walking.
This is a really great way to see Naples - we went in the Historic tour - and it gave us a taste of the history in the centre of Naples, and highlighted things we could explore later on our own. It also told you what you could get to see at each hop off point.