Faiths & Pantheons is essentially a 3rd edition version of Faiths & Avatars. The book itself is in the trademark style of the FRCS (Forgotten Realms Campaign Setting), which keeps continuity with the other books and looks good too. For the actual content - it is good. Not excellent, and if you are happy with the 2nd edition F&A book then you'll have much less reason to buy this, but if you are a DM who runs campaigns in the FR world (or simply an FR enthusiast like me) then the book is worth getting. There is more information on the deities and their avatars rather than their clerics this time around, I would have preferred both, but a lot of content was cut from the book because of space reasons (one of the factors which prevents it from reaching 5 stars). It does though, include new PrC's and three temple information sections, as well as some sample adventures with hooks to lead your characters in.
The artwork (one of the most important things) is variable - the other reason this book does not manage the 5 star rating. Some pieces are excellent, Selune, Shar, Lathander, Helm, Sune, and also of particular excellence is the Waveservant PrC. Some of the others are too bound to the mythological mind's image - Talos seems far too much like Zeus for my liking for example. Perhaps a larger section could've been devoted to non-human yet important deities, such as Corellon Larethian too.
If you combine this book with the 2nd edition F&A you'll have the most complete sources on FR religion. But mostly this is for those who didn't have F&A.