Join.me is pretty simple to use and fairly minimalistic compared to solutions like Webex.
Once the app is installed, you can start or join a meeting (share webcam and/or desktop). When sharing the desktop you can choose the full desktop (1 monitor) or a single window.
Meeting scheduling and account management is done via the website, not in the application and is simple.
Files can be shared on a one-off basis with a single participant at a time.
Meetings can be recorded (but must use the join.me conference service to record audio).
Bubbles. They introduced "participant bubbles" recently and they're intrusive. Having to spend a few minutes at the beginning of a web presentation explaining to users on how to turn off join.me features isn't a good use of time. Bubbles appear to be focused on keeping the video conferencing front and center, but if that's not being used, they're of no use.
Forced updates. When opening the desktop app, it checks to see if there's a new version (which seems to be published every 4 to 6 week) and updates automatically. So you have to get in the habit of starting the app 10 minutes ahead of time to make sure to give the app time to update if it needs to. A better method would be asking the user to "update now or upon app closing".
Audio management. There's no in-depth audio management (per participant muting, etc.) available.
No support for use in VMs. I had used join.me successfully inside of virtual machines for a number of years. With version 3 (current version) join.me no longer works. It opens but then the UI blanks out and is no longer responsive. In contacting support, they indicated running inside a VM is not supported (though it worked for years).
User account creation for desktop app. Participants using the full desktop app (which is the only way to share a screen) must register for an account. General feedback from folks has been negative at having this as a requirement for full meeting participation.
Join.me seems a bit more focused on video conferencing than web presentations. It works for both, but ends up having annoying features (bubbles) that get in the way of pure web presentation requirements.