Sonar GNU/Linux is an accessible distribution built off of Ubuntu. The versions of Sonar will be built off of the current Ubuntu releases. If you are a new user to GNU/Linux you must understand that GNU/Linux is not a replacement of proprietary operating systems but an alternative. Since it is an alternative there are some differences between GNU/Linux and the proprietary operating systems. So there is going to be a small learning curve to understand how GNU/Linux operates and is structured. There are some simalarities between the two so it is not like you will have to start from the beginning and forget everything you knew about the proprietary system you are coming from. Both systems do share some simalarities.
The best feature of Sonar is that it is Free software and if you depend of assistive technology this is the best option for you. Free software gives you 4 Freedoms that proprietary software doesn't give you,, in fact it restricts you. If you want to understand Free software then visit the FSF website to understand it completely because the FSF is where Free software began.