Once the mists of pandaria are released, you will find that all classes would have a new talent system to deal with. Some of the abilities have had their level requirements changed. While the old talent system has plenty of points to allocate, most of them are locked into preset talents for best effect, and there are few real choices to make.
The new talent system has many different and interesting abilities that appear to be real choices. While some lend themselves to certain specs more than others, they are all valid choices and you will not be out of place by taking almost any of them.
Is it brings More or Less Choice by the mists of pandaria? After looking at all of the choices in this new talent tree, you can see some real options and choices. There were a lot of talents and a big amount of choices in the old talent system, however, most of your points were locked into preset talents that were not very interesting and didn't change your character much at all.
Overall, it hasn't changed the whole part. Most of the changes to the healing spells aren’t adding anything new, they’re just building talents that no longer exist. Take druid as an example (more detail changes on farmer100 blog), based on this, you can expect druid healing style is not going to change much from its current form. And the Glyph of lifebloom which is huge quality of life improvement makes a good change.
One of the sharpest double-edged swords in Blizzard's arsenal is the constant iteration to class and play design that comes with wow expansion. On the one hand, players like innovation and new mechanics and spells to keep their favorite class fresh. On the other hand, players could reject the changes as too severe or too different from the class they originally set out to play. Do you worry about the changes will too different for you to adjust your controlling?
New and old players alike will benefit greatly from the "What has changed?" tab. If your accounts wow is a warrior, you can see how Blizzard wants returning players to acclimate quickly into the new Mists of Pandaria mindset. Blizzard is letting warriors know that a bunch of their skills might seem missing. There is a big stress points that Rage generation's mechanic has changed, and stances no longer control what abilities you can use.