I would say that Starcraft 2 does not have more strategic or tactical depth. Just the opposite, I think one of the great selling points is its simplicity.
Harkening back to the original Starcraft the actual game design is very simple:
- You gather a resource
- You build buildings
- You build units from said buildings
By comparison a game like Sacrifice, requires you to manage dynamic resources on the fly while engaging in a mercantialistic struggle for a sometimes intangible concept of souls.
Starcraft is, if anything, very normal for a RTS game. There are few bells and whistles. What it has done that few others have is take this simplicity and hone it. The fact that its relatively simple has allowed its creators to exercise great balance between its units compositions.
As for unit aspects of the game, Starcraft 2 places a lot of emphasis on the concept of being seen and the effect of terrain.
Units can often be seen or not seen depending on their approximate location to one another as well as special abilities they posses or units around them posses. Sight, therefore, becomes a new kind of tactical advantage.
The major departure in terrain that Starcraft 2 has is that non-flying units are able to overcome otherwise impassible obstacles based on their abilities (such as teleportation or "jumping"). Additionally, some units can create new impassible obstacles, while still others can remove them. Finally, terrain can sometimes be changed in nature allowing increased speed or instantaneous travel.
While these two aspects are not unique, they are given more emphasis than a lot of other RTS games such as Age of Empires or Total War (which lacks both).
As for personal enjoyment, I can't speak to what you might enjoy. Perhaps if you told me what you didn't enjoy about C&C?