I really like this game, although I need to admit I am a fan of just about most things related to King Arthur. I've been playing the game a lot recently, and am currently on my third time going through it (Played it on Easy and then Normal, and now on Hard). Before I go on though, let me explain that when I play a game with as many options or adventure/story arcs that this game has to offer, I will milk it for all it's worth, and play the living H**L out of it, exhausting my options completely. That being said, I've found a lot of enjoyment in this game, particularly since it revolves around King Arthur.
As a stand alone RTS, it is average. The game play runs well, although I can understand others being frustrated with the speed (I'm just a very patient person, I guess.) The choices you get in troops is wide ranged and very detailed. The same goes for the Knights as well (although I find that there ought to be another 1 or 2 Warlord options). When you've gotten the hang of balancing the Knights along with their strengths, it makes the game a lot easier (at least that was what I experienced during the Normal difficulty setting).
With items and weapons that become better through Battles, it quickly becomes grindfest (which I find that people either love doing or hate doing. Guess which group I fall under...? *lol*). And with the options of releasing your prisoners to be left out on the map with a pittance of an army to build from again, it can easily become very manipulative and easy to "level up" your equipment.
All in all though, I have to say that I'm most impressed with the amount of depth the game has in terms of how many different adventures can be unlocked. With the theoretical options of 4 different extremes you can take in this game, it opens up quite a bit of variety.
So if you're the kind of player who casually enjoys RTS, with the occasional grindfesting, this game is enjoyable. Admittedly, my bias and love for King Arthur mythology allowed me to enjoy it more, but even to the casual RTS player, I think this game is fun.