Actually, CL one of the reasons behind the creation of RL is to improve on RL :
- remove the need to nest for complex layouts. Nesting has some intrinsic measure/layout overhead. CL solves this by allowing way more types of relative constraint. The only remaining reasons for manual ViewGroups are performances (still faster than any generalistic approach) or really deep customization.
- solve some of RL qwirks. There are a couple of behaviors which are surprising. CL streamline these corner cases.
- deeper layouting possibilities
- integrated with a better layout editor. By better, I mean something you might choose to use, unlike the previous layout editor.
CL is in beta right now, you can add it as an external lib (that way the android team can update it anytime they want). The layout itself is already useable in production, the layout editor is where there are still some potential bugs.
The previous layout editor was pretty much unusable. Even though XML is ugly it is still efficient to work with (especially since the IDE auto completes all the cruft), so almost nobody was using the old layout editor.
The new one is still in beta and has some rough edges but it sounds like this will actually be useable and maybe even faster than editing the XML in some cases.