While the ability to use Photoshop in any capacity from your browser and, by extension, a Chromebook is good news, the downside is that it is much more limited than the full desktop version of the software. Even Adobe says in its blog post that the web version of Photoshop is there to make "light edits."
You can use Photoshop on the web in either Chrome or Microsoft Edge, and it includes a basic editing feature set for now. However, there are plans to expand it in the future. At present, the available tools include simple layers, selection tools, masking, paint tools, eraser, paint bucket, text tools, cropping and a handful of others.
Notably, this offers some advantages over traditional Photoshop as you can now share Photoshop images with anyone and allow them to open, view, edit and provide feedback on the images without having to download or install anything. You have complete control over the feedback and editing permissions when you share the link, so you decide their level of involvement. For many users, this will be the highlight of Photoshop for the web as creatives will have an easier time sharing with clients before turning over a finished project.
Photoshop for the web is in open beta for anyone with a Creative Cloud subscription starting today, and Adobe is actively soliciting feedback. Hopefully we will see the feature set expand as they work toward a full release of the product.