They seem to be preeetty preeety™ positive, with the exception of 'why wasn't this a thing sooner'. Now that the system has been live for a while, let's take a look at some player reactions to it. However, with 9.1.5 that ripcord has been well and truly pulled, as players can now freely switch Covenants (with Renown 80 on one char) and not only choose their powerful abilities at will, but also work on upgrading and unlocking all Covenant content on one character!
The locked Covenant choice has been a sore subject ever since the beta (alpha?), with Blizzard adamantly claiming it was an important role playing decision and sticking with it all through 9.1.