Just to prove I am not a total fan-boy, I do want to speak about the few things that worry me.
When it comes to some of the newer models, Blizzard has been really bad when it comes to female faces keeping unique features. Worgen Females and Pandaren Females almost all look the same, because the only difference they decided to really add to the face was different hair patterns. It's odd, since they did a good job making the faces feel different for the males of both those races, though Worgen Males have a hilariously low number of faces (I think only 5 total). However, I do understand why this kind of happens, and that's because more detailed faces the model ends up showing through more then the texture.
For example on the old models the face for say the night elf female is pretty much just a flat surface with a slight shift in position for the nose and eyes. Most of what makes the faces feel different is the texture, so you can make the nose seem "wider" or the lips "fuller" by altering the texture, and since you don't have the nose modeled in detail, or the lips modeled at all, you can get away with the texture representing those items. Expression can be "painted" onto a face through simply changing little things like the edge of lips or the shape of eyebrows, so one looks more stoic, and another more happy.
The new models won't have that luxury. They are going to have detailed lips and noses and eyes. They are going to have bones for the brows that will look odd if you put the brows in a different spot then the bones. What is that going to mean for some races? For instance, some of the orc male textures on the models we have now have different levels of teeth showing on the lower jaw, or in some cases no teeth showing at all other then the fangs. With the new model, the orc has a huge lower lip and no lower teeth showing when idle. This is going to change a lot of what certain faces will look like.
For example, this is the new idle look for the gnome female.
Now most of the side by side shots up to this point have been showing contrast, that this is what that face and texture will look like if you have the combo on the right when transferred to the new model. I won't even get into the change in skin color tone, that can be fixed, however the face concerns me. That face is one of the few faces where the gnome holds a more determined expression. The brows are angled down, the eyes focused, and the mouth straight. The new model on the left the brows are up, the mouth is stuck in a perpetual smile, overall looking like she is having a rather pleasant day.
Now this may not matter to some people, but I pick my faces based on how I want the characters personality to be represented. I picked an orc face that seemed more relaxed and grungy because I liked that personality. I made my gnome with a more stoic face because I liked imagining her taking things seriously. I picked the one undead face that didn't look like she was scowling because I wanted her to be a softer character. With the more detailed faces, they are going to model a base expression, and that expression is going to, I feel, overwhelm any personality they attempt to put into the textures, and in the end we will have an even more horrible feeling of "sameness"
Honestly, I wish Blizzard at least showed one of the models using their full range of face options (the undead male slide only showed a range of the facial altered textures), because as great as these new models are going to look, I would hate all my characters to sudden become the same looking in personality as every other gnome and orc around him/her.