I took some time time to make an "ideal" talent tree for the priest. Here is the result. What I have tried to create was a talent tree that allowed all specs to be properly represented. There are minor buffs here and there, with appropriate nerfs to prevent the class from being overpowered. I've added a few things in, and combined some talents together.
http://www.war-tools.com/t58135.html?b=9zyxe
Please note that I'm assuming that both Dispersion (the 90% reduction with mana AND health gain), as well as Holy Nova have been made trainable. Inner Fire has also been made to have no charges, with a duration of 30 minutes.
With the increases in crits, plus Grace coming closer to its original glory, plus Lightwell being accessible to Disc priests (more raid healing, rather than single target), the Discipline tree shapes up as much more of a single healing target class.
You're welcome to invent an "interesting talent" for Holy. There's a spot right there at 31 points, if you aren't pleased with Holyform.
Please be constructive with your feedback, as I took my time and put my heart into this.