I don't use Network Solutions hosting services personally, but one of my customers uses them for their email and web hosting. I use them to register many domain names though.
In my limited experience with their hosting, I have found their performance to be lacking, especially when it comes to speed.
Network Stability and Uptime The network is stable, though definitely oversold, causing sites to load slowly from time to time. I have experienced a DNS outage with Network Solutions before though, that lasted several hours and prevented any access to my clients' sites.
Control Panel Usability
The control panel is packed with features like webftp, user management and more, but its difficult to navigate and access these functions.