I thought one of the great improvements of the AHA! WOW! approache is the speed and ease to implement applications now its delaying releases for month.

It wasn't as complete to meet core CB needs as we thought it was. It needs additional functionality beyond what we used in CBSubs (that's where it started). It's not delaying anything. CB 2.0 was planned to have the lib and xml engine no matter what. Releasing without it would not be CB 2.0.

sorry but I dont understand. where is the benefit?

The entire backend will be powered by XML. We'll be able to add a lot of new features. I've already provided screenshots of an upgrade example where we've a bunch of new filters for management views (more on the way). We also have sorting planned so columns can be sorted, etc.. There's a ton of new functionality we are able to provide with simple lines of XML.

Frontend has been completely rewritten with Bootstrap 3 markup. So yes it will look and function better. Multiple usages like our Tabs JS and CB Menu JS have been completely redone, etc.. Backend is not the only location receiving upgrades. We've also upgraded Userlist with a Grid layout option and multiple new parameters. Fields can have layouts that adjust their display entirely (e.g. <strong>[value]</strong> will bold the value shown on profile).

CB Activity doesn't have anything to do with CB 2.0 as it's a plugin. All still active projects will be upgraded for CB 2.0. CB Activity will receive posting, commenting, and like/dislike features in its next major release.

Upgrading from 1.x to 2.x should be pretty painless. You'll likely need to make very little adjustments. The major issue will be our plugins as they are not CB 2.0 ready and many of them I've rather drastic changes planned (e.g. CB Conditional no longer has step by step).