Then I tried to build something using Elm and plain Html with css. Was not satisfied and tried elm-bootstrap, elm-mdl. The problems I encountered was the lack of continuing support for these packages and some other issues, like elm-mdl prohibiting the use of the time debugger feature of Elm.
Finally, I gave elm-style-elements a try. And this really is extremely promising. I managed to migrate my mdl looking project to a similar look using my own style-sheets: http://genapls.azurewebsites.net.
So, I am very satisfied with Elm thus far. I also feel that with elm-style-elements you really can create a great looking web app comparable with existing ui libraries. The only thing that bothers me a bit is the uncertainty whether packages will be supported in the future. The F# community has its community supported libraries which gives some confidence they will be maintained and upgraded. For example the elm-style-elements would be a great community supported package.
To conclude, I am really happy using Elm!