I've done about 15 000km on my "new" road bike with discs (Ultegra R785 with 140mm rotors, resin pads).
It's been mostly good, very good. I certainly am a convert and wouldn't buy another bike with rim brakes.
Consistent braking in the wet and not chewing through plenty of rims is the main thing (I am a large lad).
I was trying to think how many times I've changed pads I don't think it's more than twice, so they appear to last for about 5 000km.
...I'll make a note of when I next change them to be sure.
It's not all good though:
There is sometimes occasional rubbing, which requires caliper realignment, prodding and swearing. Rim brakes are just so much easier to adjust.
I have different wheelsets (dynamo hub & normal). There's a few micrometers of difference in the hub size, so the caliper needed to me moved when I changed wheels. (I found a solution to this: one can get 0.2mm "disc brake shims" which allow one to move the position of the rotor in relation to the flange on the hub).
Mine are QR, so maybe the thrubolt system addresses this.
Last summer I had a potentially serious disc brake incident which made me realise that there are limitations:
I was descending Alto de l'Angliru in Spain (It's about as steep and sustained as tarmac gets).
I know from my MTB days that one shouldn't drag the brakes, but going down this hill that's exactly what I did (I didn't really feel that I had a choice). I experienced major brake fade. Levers were clamped full and the bike wasn't slowing down!
A hairpin bend was approaching at speed and found myself quickly considering what solution would keep me alive and allow me to keep some skin.
I pumped the brakes and they came back to life...but only just.
Obviously one is very unlikely to encounter descents like that very often, but be warned discs do have limitations