Do not buy an underpowered machine and expect ChromeOS to somehow make up the difference and let you run apps with an acceptable level of performance. You will hate running ChromeOS on a slow machine just as much as you would hate running Windows. Spend enough money on hardware that will last the full 10 years of support. Get a fast CPU. Web apps are especially susceptible to memory bloat, so do not skimp on RAM. You will not need a large local disk for the OS. Buy storage based on your app usage only. A 2-in-1 form factor is a game changer for many work flows. I will never go back to a normal clamshell design.
I have ChromeOS, Android, and Linux all installed on my Chromebook, and I use apps running on all three environments everyday. They've done a very good job integrating the desktop environment, you'd never know you were running on different hosts.
I have never had to do a manual install of a ChromeOS update. All updates are automatic, and most do require a restart, but I've never had work interrupted because of an update. I have had to do manual updates of the Linux container. ChromeOS attempts to keep this updated, but only about 1 in 3 updates can be done automatically. As every Linux user knows, you can't avoid having to jump in and fix up a dependency.
On the big selling points of ChromeOS -- you have to learn only one UI, all the hardware just works, updates are automatic, local storage is just a cache of your cloud accounts so you can literally switch entire machines in a manner of minutes -- they've done an outstanding job, in my opinion. This is as close to set-it-and-forget-it as it gets. Much better than an Apple laptop in that regard, and miles better than a Windows laptop.