I'll be honest - the game is somewhere between mediocre and good. There are a lot of things I like about it, which are all of the good elements from previous games.
There are two main sides to the game - one side, which I will refer to as the "adventure map" side, and the other side, which is the "battle map" side of things.
You start off with a "Hero" character on a map, generally also with at least one Castle and possibly a number of forts, and your hero will have a certain number of troops. Each day of the game, your hero can travel around the map, gathering items, fighting wandering monsters (triggering the battle map) and generally trying to accomplish whatever objective the mission requires. Accomplishing this generally involves you giving certain numbers of troops to your hero(es) and sending them out to vanquish whatever happens to be in your way.
There are an absolute smegload of items, various modifiers for battles, upgrades, hero skills/talents, weapons for your hero, magic spells, and more things that can influence the result of these battles, but at its core, the tactics in the battles are what matter - it really is possible to win battles against larger armies if you have the right tactics (and possibly a couple of very powerful spells or two).
However, the main cons of it are that it requires/uses the Ubisoft always-online DRM, despite being mainly a single player game, and additionally, has only had one bugfix/balance patch since its initial release 6 months ago... and that took 3 months to get out, and should have been out within the first couple of weeks as there were a number of game-breakers in there (like the upgraded version of the Griffin's special ability NOT ACTUALLY DOING ANYTHING)
If you like, I could go into more detail about the game as that is only scratching the surface, but I do still find it enjoyable despite its faults, and although I don't play it often, I do keep it installed as I find that I actually play it in spurts from time to time, where for a couple of weekends in a row it will be the only thing I actually do...
And at 50% off, it will be £15