The reason I liked it was precisely because how long it took. Also, the barbarian hoarde was pretty un barbarian, it instituted the emergent states through the dissolution of the holy Roman empire. Really, Gibbons was sort of wrong. The invaders became "us" in almost every sense. Sucked to be Roman, but then.. it didn't.
Very few of the "lost arts" were truly lost. I could have gone to the democratising effect of the rise of Islam, where much "lost knowledge" was recovered in due course but that's a whole other story (depreferencing inheritance over functional ability)
The key point for our functional decay as a society might be the ubiquitous rise of cynicism combined with increasing joins over gerontocracy and kleptocracy.
If we are in a Rome scenario, the good news is that we probably won't live long enough to see the real collapse.