I find Energia suitable for many most of my projects. Much of the time direct register access is not needed. But if you keep at it long enough and stretch the boundaries of what others have done and posted, then expect to encounter the limitations of Energia / Arduino or at least the need to understand what is happening at the register level. It may be in terms of the software, the libraries, slow execution, lack of access to features, or that your desired microcontroller does not have an Energia port. If you learn to directly access registers then all peripherals and capabilities are available. If you want to understand and port other libraries that use direct register access then clearly a deeper understanding is needed as well. As long as you don't introduce a conflict then direct register programming and Energia work together fine and it is not one or the other.
I would start with CCS and the workshop that L.R.A suggests if using the G2553. There are also tutorials on using CCS. I find the debugger in CCS invaluable even when using Energia. Gaining familiarity with the datasheets, the family user guides, and header files was the most difficult part for me as I have no microcontroller or C/C++ background - but they are key. My approach was to become proficient in Energia and then add the more traditional approach as I went along. I even find that myself writing everything in CCS without Energia from time to time now