If you are interested in getting this you may want to hold off for a while. I've only played for about 3 hours, but:
I picked this up last night and attempting to play it has been an exercise in frustration. I've had multiple CTDs (at least 5)and it shut down my computer when launched once. It may be compatibility issues, but judging by the quests it is sloppy programming.
I've only run into 3 of the new quests, but 2 are buggy. There is a new quest at the mage tower right near the start where the dialog options don't correspond to what is going on. There is a new military academy feature and the first quest from there is unclear and the progress listed in the quest log keeps fluctuating.
The new units and spells look interesting, but I haven't had much chance to use them. I've rather liked the series so far, but this one is a disappointment and desperately needs fixing.