When comparing Gosu vs raylib, the Slant community recommends raylib for most people. In the question“What are the best 2D game engines?” raylib is ranked 36th while Gosu is ranked 50th. The most important reason people chose raylib is:
Very good for begginers who are looking for game FRAMEWORKS.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Lightweight
Gosu is not a game development framework, only a media library that happens to be suited to game development. (Kind of like SDL in the C world.) That means the interface is relatively small.
Pro Mature API, actively maintained and developed
Gosu has been under development since 2001. It is mature and has several toolkits built on top of it to provide additional functionality.

Pro Cross-platform, even mobile, using Ruby
Pro Simple
Very good for begginers who are looking for game FRAMEWORKS.
Pro Support forum
Though it's a small project, it has a forum on the webpage with helpful content available.
Cons
Con Deploying Ruby apps is a mess
Games built with the Ruby to .exe "compiler" do nothing more than extract your source code and Ruby.exe to %TEMP%, then run it. The code is not really compiled at all. The process for wrapping games as Mac apps is a bit nicer, but you'll need a paid Apple Developer subscription to code sign the app, or users will see a warning/error when running your game.
The only way to really compile Ruby is to use RubyMotion, which does not work on Windows and requires a paid subscription on top of the Apple Developer one.
(This Con is not specific to Gosu. Deploying Ruby code has never been fun.)
Con Just coding
Lack of an interface, visual help or auto-debugging could make it difficult to use for a complete beginner.
