Mistwell
Crusty Old Meatwad (he/him)
Older edition adventures are a goldmine for running 4e. The most time-consuming part of fleshing out an adventure was always (to me) statting out the combat encounters. With access to the online compendium and the ease of adjusting creatures, 4e reduces that time investment substantially.
While I don't expect wotc will publish 4e stats for all their 5e adventures like they are with the Sundering campaign, I still feel they will be a valuable resource for the 4e DM.
For me, the biggest problem I ran into with adapting older adventurers to 4e was the small rooms and corridors. 4e powers assume a lot more room to maneuver than older editions, and I found many old adventures and modules simply didn't work great with those powers. Which is OK, but it also meant that newer good adventures were more in demand. And, that was rare. I mean this site right here made some great adventures for 4e, but aside from EnWorld, third party support was not strong, and WOTC's own published adventures were not particularly strong on average either.