When comparing Irrlicht vs Shoot 'Em Up Kit, the Slant community recommends Irrlicht for most people. In the question“What are the best 3D game engines?” Irrlicht is ranked 49th while Shoot 'Em Up Kit is ranked 55th. The most important reason people chose Irrlicht is:
Many working examples to study and learn. You can easily experiment modifying an example code to grok in full how the engine works. In the beginning of your learning curve, the example code will offer you many useful code snippets.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Lots of examples and docs
Many working examples to study and learn. You can easily experiment modifying an example code to grok in full how the engine works. In the beginning of your learning curve, the example code will offer you many useful code snippets.

Pro Free and open source

Pro Good polymorphic design
If you are considering writing your own engine with openGL, you might want to consider Irrlicht instead. It makes many features of any engine worth its salt easy, including events, serialization, nodes, animators, materials, logging, and animation. Bring your own sound and networking.

Pro Lightweight
Especially if you compile it yourself, it can be very light in memory usage.
Pro Easy to entry level C++ experience
If you want to start game developing with C++, then Irrlicht is a good candidate since it removes most of the complications in game making in C++. It will let you obtain experience in programming and games at the same time.
Pro Support for multiple formats
This engine supports multiple formats for 3D objects and textures.
Pro NPC Generators
Control NPC spawning position, frequency, maximum enemy active at once, and maximum enemies created by the generator.
Pro Support for user-created HLSL shaders
Both model and post-process shaders.
Pro Great for shoot 'em ups
The name fits the functionality.
Cons

Con Outdated
Obsolete over 5 years ago. While the engine is being worked on with plans for new features and support, the movement is slow, leaving many engines far more advanced in certain areas.
Con Not a game engine
This is a 3D graphics engine similar to Ogre3D. Thus, it doesn't provide any pathfinding or physics support. Support for those will have to be added by the dev.
Con Lacking some details
No information on file formats or codecs in the manual.
Con Tutorials are too short and too old
The only real tutorial videos are 1 or 2 minutes long, and date from 2013.
