This expansion is for C&C fans only.
New missions are really tough, don't even try it if you haven't yet completed original C&C campaigns. AI is going to strike you intense, however same old tricks like sandbag rush is working. I used it on one GDI mission, which is almost impossible to accomplish. Mission goals and design varyed greatly. Some missions are about building a base and destroying enemy, but some are really interesting and innovative. Like the one where you have to free villager's wife and so he would discover the location of important enemy building for you. There are more interesting situations you may discover if you want. Single player missions include units that was rare or wasn't used in single player of C&C like toxic troopers and V rocket launchers. Also lots of missions includes commando.
Most interesting feature of this expansion is Fun Park missions. They can't be played without changing executable file. Fun Park mission takes place on some kind of Jurassic Park, you take command of nod forces and have to fight with dinos. 5 cool missions, special intro video with Kane also included, that is the only new FMV in the whole expansion!
Unfortunately Covert Operations have no new units at all (except dinos) and no new videos (again except dino one). This makes expansion's value very low. It will be interesting only for those who want more of original C&C gameplay, which is still great and highly addictive.