Overall, I'd give it a 6 out of 10, but I only have a yes/no and I save "yes" for things like Half-Life 2. While obviously dated, this is more of a "fun" RTS than a good one. If you like the idea of essentially playing commander in an old, zany James Bond movie from back in the day, you'll have fun with the campaigns, and I did enjoy those pretty well, though many missions are easier than they ought to be. Inevitably though, I'd describe it as the bridge between the quite good C&C3 and the infamously bad C&C4, with its quality falling somewhere in between that. Buy it on sale if that seems interesting.
If you want to know more about its problems, the game not only features a UI downgrade from the C&C 3 game that preceded it (where's my assault move?), but has additional problems with pathing and responsiveness that I've never noticed in that. It's very aggravating to attack move with some submarines to counter a carrier for instance, go put out a fire in a ground battle elsewhere, and then look back to find out that your subs have hardly moved and are instead attempting to beach themselves while that same carrier has just gone on with its rampage. Units also have much sketchier target acquisition and prioritization than they do in that game; I've often seen my "anti air" jets idling hardly any distance nearby while one of their squadmates, for some unknown reason, wandered off slightly despite receiving the same orders, and is now fighting several other anti-air jets on its own. Worse yet, the balance is very dubious, if not outright bad. "Counters" are often inefficient and in many cases can't even trade effectively, ironically causing you to end up losing resources while the unit (usually a bomber) simply repairs and comes back, netting a flat economic loss. I suspect that this is because unlike in a more normal RTS, the math appears awfully linear instead of the more typical "this thing can take out two of these other things for the same cost," and yet the design nonetheless features mostly specialized units and a pretty limited amount of resources. All sorts of utterly frustrating scenarios can unfold from this questionable choice, especially in anything outside of one on ones. It honestly tends to be more maddening than fun outside of the campaign setting as a result, and I say that as someone who has probably played more games in Kane's Wrath than I really ought to have in one lifetime. They're simply not the same quality of game, unfortunately.