Game Maker isn't just about drag and drop.
If you actually aim on making a good 2d game you have to use the GML language (Game Maker Language). Which has similar syntax to java, c, c++.
You said you know Java so its going to be easy for you to get used to it and get started quickly.
I personally use Game Maker and I think its an awesome tool for making 2D games. (ONLY 2D GAMES!)
I have never used the Game Maker Drag&Drop tools cause I find them more difficult and limited from the actual scripting language.
It also supports multiplatform (andoid,iOS, windows, html ect.). At a given price of course...
If your aim is 2d game development then I think Game Maker is a good start.
Personally I started learning Game Maker from youtube videos of Shaun Spalding, When you get how things work you wont need any more help. Then it will be up to you. And of course there are game maker forums to help you out for more specific things,
Hope I helped.