Do they hold up to today's standards of detail - absolutely not.
They are "shake the box" kits so "building" them isn't really an issue.
Brand new un-built ones on e-bay are going from $6 to $26 depending if they are straight Athearn or if they are like Bev-Bel or other custom paint.
Having said that. If one is going to be doing some serious operating of a layout, especially with other folks running the trains, you want a nice durable cars like the Athearn BB and Roundhouse that can take the punishment. Some of these new highly detailed cars for instance by Scale Trains and Rapido get broken just putting them onto the track, let alone in a wreck.
How much detail do you NEED is the real question. I can pretty much guarantee 95% of the non model railroad folks viewing your layout
I have many Athearn BB and Roundhouse kits stored away waiting to be built; do they still hold up to today’s standards? Are they worth building? How much are they worth today (on average)?
I’m talking about rail cars, so locomotives do not count.
For those who are asking about detail, I don’t really care as long as it looks nice