MonoGame

What do you like best?

MonoGame is easy to pick up and understand. It provides enough features and tools for game development out of the box, without getting in your way like Unity or Unreal. That it's open source at this point is a huge bonus.

What do you dislike?

It is a framework, not an IDE, so you have to find online or build your own game development tools / processes, like a level editor. The learning curve is difficult with 3D games versus using a game engine like Unity, but since you have complete control of the code, you are free to come up with your own solutions. Support seems to vary for the framework, and there seems to be daily builds with updates, but only one stable release build a year.

What problems are you solving with the product? What benefits have you realized?

I use MonoGame for personal game development as well as introducing my computer science students (entry level college class) to frameworks and game loops.