Originally Posted by Eyrie

I uses buses a lot in London (within zones 1-2), and pre-pandemic on a daily basis. Google maps is generally ok for arrival times as long as you don't expect it to be very accurate (assume a few minutes' error margin). What it's useful for is to see the general frequency of buses (are they coming every 3, 5 or 10 minutes). Tfl website is much more accurate but a bit more hassle than google maps unless you save your regular bus stops under your "favourites", so I have stopped using it.

Buses take longer and you can get stuck in traffic (or the dreaded "this bus is on diversion" where it's up to the gods how much longer your journey takes), so for anything time-sensitive it's worth taking the tube. If your trip is only within the very touristy-shopping part of London, the bus can be slower than walking for some streets.

But overall, if you don't mind spending 20mins more on your trip, getting a seat on the upper deck is a nice way to get a sense of the city and you're often more likely to get a seat on a bus than on the tube.

I use my bus-commute to read, and losing 10-15mins compared to taking the tube and having to change twice is nothing - it's my preferable way to get to the office when I decide to go in nowadays