I'll give you my personal 0.02 on it, since I did use GM at one point; and I started for the same reason, that a game I really like (the original Spelunky) was programmed in it.
I'm not going to weigh in too much on the whole EULA and royalties aspect of it. IMO, if you are going to use an engine that has already provided you a ton of tools and thus saved you a lot of time, it's okay to pay a percentage to the engine maker, I'm okay with that. The smart business decision becomes getting the most engine (free work) for the least royalty (loss of potential profits).
I used GM for a little bit, bought a bunch of books on it, learned its quirky aspects. When other anons say that it has a weird system for code, they are not lying nor exaggerating, some of the stuff like the room system is kind of weird and can be a pain in the ass.
The editor can be buggy and kinda shitty at times. True story for me: I found a tiny bit of code online to solve a problem I had been having. So I copied and pasted the code into the editor, made a few modifications, and then tried to run it. It gave me a compile error when there shouldn't have been one. I was like, what the hell, and proceeded to do a bunch of debugging for hours. I was banging my head on the keyboard trying to figure out what the hell was wrong, and in desperation, I tried typing all of the code back into the editor, by hand, from a notepad file. It worked!
So I investigated as to why it wouldn't compile the first time around, and went back to the webpage that had the code and I tried copy and pasting the bit again, and it wouldn't compile. So I took that bit of code and pasted it into another program, and there it was… An invisible character. One random invisible character that was put in for formatting or something by the webpage was copied and pasted into the editor, and the editor wasn't rendering it, but the compiler was trying to compile it. I had literally spent hours trying to hunt down an invisible character for code that should have worked the first time I ran it.
I kinda stopped using GM not long after that, that wasn't the main issue, just one of many stupid buggy things you would run into all of the time.
That said though, it is easy, and if you have never programmed anything before, you could use it to get started and learn kind of how a game works and how to program one.
But to use that as your main tool that you will have rely on forever, I think is kind of a mistake, IMO. It forces you to do things a certain way that only GM does, so if you want to transition of it later, you need to retrain yourself and forget their inefficient system.
I switched from GM to Unity. Also had issues with Unity, switched from Unity to Unreal, and I'm very happy with Unreal now. I wish I had just jumped into the deep end with Unreal from the beginning years ago, I would be much farther along now.
But like the other user said, don't take my single post as gospel, try out a few packages and see what clicks for you.