I used one quite a long time ago. The audio quality was pretty good, but it really can be improved if you use an external microphone (for recording conversations). But for quick comments, it was very useful.
The downside was the process for getting the file onto the computer. The Sony software (and user experience on the recorder itself) was not very good. And, the software may not work with "modern" systems.
If you have a smartphone of some sort, you may have a voice memo capacity built in or easily added with an app. For example, on my iPhone, I can use the voice memo feature (built in) or record into Evernote.