Yes. As written, things are pretty linear and it's not hard to have the players fall or be pushed off the rails.Sounds like prepping side encounters, making urban themed maps, etc, would be a good way to spend my time?
Yup. I've had to do that before, in both 2E and 3E. Though do stop before you start. It's pretty awful if you go a few adventures in and then just as it gets interesting, the DM is like "Ugh had enough of this!" (I've been on the wrong end of that before, sadly).But you're totally entitled to tell your players, sorry, you're not interested in running it. That's what I did with Tomb of Annihilation.
Yeah, my experience running Dragon Heist started off great because I poured a ton of time into preparing, including bringing in a bunch of new content. Then toward the end I got lazy and tried to run it straight from the book, and the campaign got steadily worse.As someone who ran Dragon Heist, and it was actually the first adventure I've ever run for 5E, I find it FANTASTIC.
It definitely gets a bad rap, but it's only uninteresting if you run it EXACTLY like how the book says. What you should do instead, is use the book as an outline, and feel happy to deviate from it and improvise whenever you feel appropriate.