The shortcomings of the Chrome OS screencast recorder are the limited drawing tools and limited editing tools. It will probably get better in time, but right now it doesn't have nearly as many drawing and editing options as other screencasting tools like Screencastify and Loom. 

Here's a brief video overview of the Chrome OS screencast recorder.              

Screencastify was one of the first screencasting tools developed specifically for Chromebooks (it should be noted that it can work on any computer running the Chrome web browser). Over the years it has improved in leaps and bounds. Today, Screencastify offers more than just a tool for recording a video of your screen. It offers a complete video editing platform. 

With Screencastify you can record your screen, use a wide variety of drawing and zoom tools, and edit your recordings in your web browser. Recordings can be automatically saved to your Google Drive account, downloaded as MP4 files, and shared to other services including Google Classroom, YouTube, and EDpuzzle. 

The editing tools in Screencastify include cropping, splitting, and merging clips. It also provides tools for blurring faces and objects in your videos. Finally, you can use Screencastify to build must-answer questions into your videos before you share them with your students. 

It should be noted that on October 3, 2022 Screencastify introduced some severe limitations to the features mentioned above for those who are using Screencastify's free plan. Those limitations include a limit of having only ten videos in your account, a limit of only 30 minutes of export time (the total amount of video that you download from your account), and videos can't be exported as MP4 files. Those limitations make Screencastify's free plan not nearly as a good an option as the Chrome OS screen recorder or Loom's free plan for educators.