If you don't mind, I add Foundation by Zurb in the topic (the only true valid alternative to Bootstrap at the moment).
I just checked the project/framework SemUI and it's pretty awesome. The idea of building your pages in a strict semantic way is obviously good, moreover the design is stunning in my opinion and there are a lot of components and settings to use and to choose from the set.
Another thing that I noticed is the package, very well organized, every component if you want has its own stylesheet and script-file, therefore you'll be able to load only what you need, even because the package is quite heavy if you include everything in a single page.
For a pre-release I admit that I'm considering to build my next web-app with such framework, but I got some perplexities:
- is that mobile-first like Bootstrap or Foundation? from what I'm able to see, it doesn't look so;
- Bootstrap has two valid and well-known contributors and Foundation got Zurb behind, what about SemanticUI? this is a pre-release, are we gonna see other releases?
because of such perplexities I think to avoid to use it for a business/commercial project at the moment, maybe in a very near future, but if you're planning to use it for your own personal web-app (like mine), I think it's a pretty good choice.
Then if you wanna fallback to Bootstrap for any reason, I think it's not that painful (many of Semantic components seem based on Bootstrap).
