On its surface it is not complicated, it is designed so anyone can go in and play. The matchmaking system will ensure that you mostly play with other people on your level.
However, competitive SC2 is huge and people make livings playing it. It is supremely complicated at the top level with many layers of strategy. However, unless you are very very good at it and intend to put a great deal of time in to it you will never do more than brush up against that stuff.
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If I have burnt my bridges I will walk on water.
If you're on the shore, then you're sure not me, oh
My seething wrath and urge for blood is fueled by searing hate.
I'm X X X bitch, triple X rated.