It's different, it's interesting, it's disappointing.
Fighting as a dragon is about as awesome as you might expect, and takes longer to get tired than you might think, especially if you set yourself a good range of skills. You have limited army control in this mode, so can at least fight with a thrash of units under you, radiant in the healing, damage-boosting auras you emit.
But you can basically forget trying to play the RTS as designed, because someone put this on top of a Starcraft-y set of units with lots of manually-triggered abilities. You might occasionally switch your artillery in and out of deployed mode, or tell your tanks to use their short-range sonic burst attack, but not much more unless you forego being a dragon. And then I have to ask why you are playing a game whose main defining feature is that you are a dragon.
One reason possibly being for the challenge (and inevitable achievement). The dragon is basically like spawning with a Supreme Commander Experimental right at the start. You can assert almost total control of any one point on the map. It's rare for an RTS battle to last more than a few minutes, and if you lose it's because you just got overwhelmed by the AI's ability to multitask harder, or bit off such a ridiculously one-sided starting position that you got rushed while the dragon was in its first-minute cooldown.
On the strategic layer, you can only fight personally once per turn, and the rest is up to autoresolves, possibly modified by generals and cards. There's some depth here, especially in picking which fight you want to be your certain win, but nothing to get ecstatic about. Units are almost too mobile, especially naval ones which loop around the map, for territorial control to mean much more than "keep units on every tile". An offensive force headed by your dragon self can steamroll forward so much more effectively than any other that there's limited utility to fighting on multiple fronts.
The diplomatic side is basically brilliant. Characters are well-written and well-voiced, although the fact that every choice is binary is oft irritating; there's quite often no room for moderation or nuance. You probably won't want to put up with the actual *war* part of the game long enough to play it through enough times to see everything, and savescumming a bit just to see branches not taken is confounded by several turns' worth of delays between action and consequences. Turns padded by war.
The ending is flat as a pancake, however. You capture the last key territory, everyone says well done in turn, title screen.
And the multiplayer side? Ridiculously crippled. Pick from one of three predefined dragon loadouts (despite loadout-building being a key fun part of the singleplayer), four players per map tops, no AI dragons, only armies. (It's not much of a spoiler to get the disappointment out of the way and say that nothing of the sort shows up to peturb the mix in the campaign, either. There is no climactic final battle here, just another identikit skirmish.)
Get it in a sale, enjoy the council going at each-other's throats, and divebombing down onto massed enemy forces to unleash a huge firestorm amongst them before swooping around to gather your own army and charging forward into the enemy base with a bellowing roar. The ambience is great. Just expect by the final chapter to be looking at the strategic map with a weary, tired eye that just wants to autoresolve but knows the Imperial Army will blow a 70% chance and get driven back, and occasionally wishing your conversations didn't feel so railroaded.