I do not care for the Batobus, which doesn't give you any view at all of major monuments, etc.
It's on the river level, so it's like looking up from a ditch.

I think those seasoned travelers who dismiss the HOHO bus have forgotten how daunting it can be to navigate an unfamiliar city via public transport. I am very familiar with Paris, but I still sometimes spend a lot of time figuring out which bus to take and where exactly the bus stop is. I don't know London at all and I cannot wrap my head around the oyster card and other passes. On a first visit, with little time to spare, the HOHO bus gives you an easy overview of the city with lots of information about what you're passing by. When you ride the regular buses you often have no idea what you're looking at, and as has been pointed out, in the metro you're seeing nothing of the city.

On my first visit to a city, I often do the HOHO circuit the first day, then return to the sites that interest me on the following days.

A good orientation to London visually is also garnered from a ride on the London Eye observation wheel (don't call it a Ferris wheel!) - each car has a map showing you all the landmarks - Eiffel Tower similarly so in Paris - not saying a substitute for HOHO buses which have their pluses and minuses -especially in London with its notorious traffic snarls.

Fuzzbucker calls the Seine a "ditch".

Gliding on that river, after dark, with the lights of Paris all around you? Priceless.

Different experiences, different opinions.

I did HOHOs when I was less experienced. It was even more of a waste then. IMHO, the less time one has in a place, the less time they have to waste riding around on a bus. Yes, it takes a bit of time to get oriented in a new city, but the two or three hours of time spent on a HOHO bus would be more than enough time to learn how to buy tickets, work out bus and metro routes and then actually see one sight - some great church or monument.

Also, agree with MoBro. Evening on the river, looking up at the lights of Paris, is magical and romantic.

Use the app Citymapper to navigate an unfamiliar city. It tells you how to get from A to B using different modes of transport, which bus, how long it takes to arrive, how much it costs. Very easy to use.

HOHO buses in London are generally a terrible idea. They just sit in traffic for long periods of time. We have done them with friends who wanted to when visiting us and most times we have ended up hopping off (sometimes after sitting in one place for 20 mins) and ditching them midway through.

Another waste of time is having bus after bus go by full, or having to finally get on one and sit below where you can't see anything.

It is a much better use of time to pick 2 big sites a day and then have lunch, maybe go to a show in the evening.

I did not state that the Batobus should be used in the nighttime.
I said it is useless to use the Batobus in the daytime, when it is indeed, in "ditch level".
It's expensive for what it is, and you'd do much better to take a city bus.
As the website states, it runs in low season from 10 to 9 PM and in high season from 10 to 9:30 PM

I've done the HOHO in Paris, usually after we've walked so much our legs need a break. It's a great way to see the city and the sites you don't have time to go through.