If you're looking to spend $400+, then you should get a real laptop.
The chromebook OS is impressive by netbook standards, but the software support outside of running a web browser is essentially "none".
Chrome OS doesn't have a native app store. It's the Android Google Play store with a couple dozen or so native Chrome OS apps buried under 10-million emulated android apps which absolutely will not work with a mouse/keyboard, and often won't even work with a chromebook's landscape aspect ratio - and that's if they even launch in the first place.
There also is very few games made for chromebook (it didn't even have a real version of minecraft until a few months ago) - which is fascinating considering it's massive install base. More kids have chromebooks right now than Nintendo DS ever had at it's peak (and even the worst chromebook is a lot more powerful than that). I don't know why game companies seem to be ignoring the platform.
So you're back to "I hope this android game will launch and let me technically navigate a menu without having to plug an $80 gamepad into this $80 laptop"
Most importantly, there's no tools to filter or search the Play Store for native apps, or even by the features of your chromebook. So if you don't have a touch screen, good luck finding apps that you can interact with. Side-loading Linux apps is possible, but also a broken-driver terminal nightmare.
Chromebooks are neat toys and kindof fun sometimes. They run a web browser way better than you would expect out of terrible hardware. Really my only complaint with the web experience (and native apps when you can actually find one) isn't that I'm running from running a 1.6GHz dual core celeron from 2013, it's that 4GB of RAM is only good for like, 6 tabs of modern websites before it runs out.
Still, it doesn't make any sense to spend more than $150 on one. I don't think this weird Chromebook Plus branding is going to make overpriced chromebooks worthwhile, unless it eventually comes with a complete ground-up redo of the software library and a native app store.
Maybe the bad hardware was stopping them from improving the software library, and maybe Chromebook plus is going to be a baseline new platform to improve things in the future. But I'll believe it when I see it.
Right now it feels more like "Give us 3x more money for the same basic limited user experience, with a slightly better screen".