I got one, as did some (but not all) family members also in AGR.
I used two of them to upgrade a pair of us from Virginia to a smaller New England station with no issue (8 hours travel). I simply called the evening before a morning departure and got it done easily. Knowing the ticket window "competency" of the local stations, I would NOT have tried to print it and do it there - they basically can sell a standard ticket and grudgingly give you other basic info, but that's about it. To me, asking for an upgrade processing from a discount ticket would be a non-starter.
Agreed there isn't much to get excited about, but my past times in Business Class have included a quieter ride with a bit more space and free coffee - more than one cup, actually. Anyway, worth the call, 10 minutes of hold to talking to a nice lady who took the certificate numbers down and immediately emailed a new ticket for those better seats.
In the past, I have also had upgrades given to me twice: once I did it on Regional (equally as easily and comfortable) and once on Acela on a midweek 'business' city trip with no issue. I might have paid the dollars for the Regional upgrade (like $30) but not the Acela ($150). Acela First is great, but not that great. To each, their own.