I have two chromebooks. ASUS 302 and acer spin 11. spin 11 is good, sometimes a bit slow but decent. The 302 is really good and I don't mind tablet mode. Touch is not a good as an iPad but overall its a good machine. Chrome OS is lacking some basic things that come with MacOS and iOS which means I use a MacBook for everyday. if it had a good basic iMovie competitor and a good PDF viewer with markup and signatures, then I would say I could lose the MacBook.
The ability to log in to a new Chromebook and have everything download and sync is the killer app.