No cons, pros: If you have to reapply for another cycle or use those letters for another program such as a masters then you have your letters in hand and dont have to request them again and wait for your professors to take forever. I had no issues with interfolio aadsas.
Inter folio as you can set the due dates yourself and send reminder emails that come from Interfolio. Also you can keep them forever and not locked into the App.
Interfolio has instructions on sending the letters you collect there to AADSAS. It’s super easy and convenient, and the letters are stored for you. Worth the $50 imo