Take a step back when booking, though. It can suggest trips with tens of connections without taking delays into account (and it's rare, if not impossible, to not have some delay with that many connections).
The reasons I didn't went to it was because I couldn't see my self sitting for so many hours a day.
But I guess my destiny was different than I expected.
A few months ago I got an offer to participate in a 22,000KM journey called the 'Mongol Rally' which is basically a race when you need to drive from the Czech Republic to Mongolia in a shitty car.
Joining this race meant sitting in a car for at least 14 hours a day
I agreed to the offer without thinking twice
and after I finish it, doing the Trans-Siberian road looks like a piece of cake
In my case I had only 6 weeks for the Mongol Rally so we drove every day 14 hours in the car
I'm not sure how long it takes to do the Trans-Siberian route, but if I will do it I will make sure I have enough time to have few days in nice places along the way.