Plenty of replies here so I'm sure you have a decent idea what this is like, but here's my tuppence:
Had a root canal around 7/8 years back. One of my back teeth had eroded quite drastically and it was 50/50 as to whether it could be saved.
In all honesty it wasn't that different to a regular filling- in the chair for a bit longer, a lot more drilling (which you don't feel, mainly vibrations through the jaw). Due to not being able to see your mouth you can't see the images you've possibly looked at which can look a little scary.
All-in-all it wasn't that bad. Cost around £100 I think (might be wrong, it was a good while ago).
Couldn't eat anything too solid for a few days afterwards whilst it healed, no biggie.
Experiences I guess will depend on the individual case, mine was ok though. Tooth saved and no problems :-)