I have tried Beta 1 and just installed Beta 2. Very promising so far. I installed the Beta on the same computer as my copy of C1 3.7 LE and the Beta uninstalled 3.7. I suggest you try the Beta on another computer if you are currently using C1.
i tried it on a mac, dont care for the changes at this point. and it didnt uninstall 3.7.7.
new images seem more noisy at default settings. im used to the sessions organization and there are many settings/controls that repeat over several of the tabs/pages now...dont know why they did this.
I am having tremendous problems with it on a PC, and have told Phase One that it is virtually unusable. I am not the only person. My advice is to install it and try as it will not affect 3.7.7 but do not rely on it.