The fact that it's very light-weight. It's easy to use. It's great. The support is fantastic and the documentation is really good. Slim doesn't support all of the MVC frameworks, but it's more of a general framework, so there are some downsides with that. I would recommend using this framework for your web development. It's very easy to use, and you can do a lot with it very quickly. Really good for small to medium-sized projects. I have been using Slim for about 2 years now, and it has never let me down. It's very easy to use and implement, and I love how lightweight it is. It's also very well documented. You can easily find tutorials online if you are stuck. Nothing in particular. The documentation could be improved, but it's not bad at all. I highly recommend this framework! It saved me a lot of time coding my API.