>>345687439
half of the stuff that was in the left sidebar is still there but as icons (hit T to toggle). the other half (including things like CATS) are now in the right toolbar which you toggle with N.

There are some nice video tutorials for 2.79->2.8 changes as well. I won't say the changes are not confusing and annoyingly arbitrary at times, but it is worth it to take the time to relearn.