If you want to see the Trade Domian in action we are using it here: https://www.twitch.tv/savioursdnd Buy it! I have been using it for over a year and really like it!
After using this book for several months and reading all the different variants of priests I have to say that this is the best options book I have seen for a long time. It grants loads of individual options that are accurate to your clerics god, grating you a deeper and more interesting game play. Rather than a simple “1+ to trade” that my Cleric of Waukeen probably would have gotten, Instead she got a more interesting effect to use in trading and in using languages. Its very interesting.
I would also recommend this not just to players who want to play a cleric but also DM’s who will feature Clerics or priest in anyway in the campaign, as it contains some more defining info about the gods and some abilities that could be interesting for the party. The Forgotten realms is a campaign that is steeped in gods so having this helps with the wide variety of gods that are in there but it's also good for another campaign to add more flavour the priests that might be in it.
It's hard for me to state how wonderful this book has been to use in my group as I have used my cleric of a rather unusual faith (waukeen) to make the world feel more alive and more interesting. I am able to solve problems and find solutions in more interesting and innovating ways. I always recommend it!