I disagree with GG being "hard as hell" to get into, imo it has an unfair reputation of being very difficult.
And when talking about being really good at GG, it's true that there is a lot to learn and you really need to spend time on it it if you want to get far. But I also think GG is very kind towards low level gameplay, the game has some strong defensive options and good fundamentals can get you places. You just need to start off with the basics and take your time with harder things like FRCs.
I would personally recommend GG over UMvC3 as a starting point, low level in GG is not complicated at all.