It's been a long time since I messed around with ADRIFT, but I love version 5.0!
I've been away from IF for years now, but I recently introduced my 11-year old daughter to some of the old Infocom games. After playing through HHGTTG, I found myself wanting to create again.
I think the ribbon-bar is a great addition and the 3D map makes ADRIFT look much more professional.
It just feels smoother and less clunky than 3.9 and 4.0.
I have found a couple bugs, and as a developer myself, I have noticed some things I would change, but those things are mostly my opinion, and do not affect functionality.
The big, in your face icons and tree folders stand out and tell you exactly what you want to know.
Overall, I love it.