How good is the basic gui support and besides scaleform is there any good gui solutions ?
There is no Scaleform support by default in engine. If you want to use Scaleform, you need to buy license and integrate it on your own.
The only build in options are:
Slate - if you are willing for now make your UI using C++.
Canvas. It can be done trough either blueprint or C++.
From those two I would really recommend using Slate. It’s going to be daunting at first, but you will quickly appreciate, that most of common UI problems, has been already solved for you, and all you need is to override some virtual functions, and think a bit about structure of your data for UI.
Where in Canvas, all you can really do is… Draw UI. If that is all you need then canvas is your best bet.
But if you need some more advanced functionality, like window dragging, drag&drop, animations, Slate will be better.
There are also other third party UI solutions like CoherentUI and Radiant SDK.