i'm interrested in starting to learn abit about graphics programming through game development and i'm wondering what the pros/cons are when using Unity 3D over using something like C++ & openGL
It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. If this question can be reworded to fit the rules in the help center, please edit the question.
asking Unity3D vs. C++ & OpenGL is like asking whether to buy a Car vs. or a Wheel. You either know how to build a car using it's parts or you need to use already built cars out there!
Unity 3D is an integrated development environment for game development. C++ and openGL are just tools you can use for game production.
It's hard to compare them because of that. For starters I'd suggest you finding a 2D game library for your favourite language and only then switching to c++ / openGL when you feel ready.