Well, we've only had them for about a week, so I can't vouch for anything over the long-term. However, compared to the GameServers panel, it's very extensive actually. Their public webpage is very minimal, yes, but they have treated me very professionally as a customer. For example, when we originally ordered the server, we were getting regular lag spikes that weren't caused by our plugins. They got back to me within 24 hours of me emailing, and said that though they could not see anything wrong with our server they'd move us to a new box. After the move, our server was working perfectly--as you can see if you join it. I have gotten several automated emails from them (which I appreciate). In one, they explained that another customer's account had been hogging the pipe and that they had shut their account down, so service should improve.
They actually update the servers automatically for you, unlike gameservers. They have a script which waits until the server is empty and then performs the update (or, they say, you can restart the server for it to update).
About the panel:
Their panel has a lot of information and different sections. Status pane shows map, players etc. Server usage pane shows graphs of the player count over the past day, week, year and month. Server health pane explains the OS, CPU, memory, memory usage, CPU usage and uptime of the entire machine. Events log shows past events (updates, restarts, news posts).
The "easy setup" panel allows you to change the hostname, rcon, logging, timelimit, mapcycle, and sourcetv settings directly in the panel. They have a page for installing mods and plugins automatically: CEVO configs, EventScripts, HLSTATSX plugin, Mani Admin Mod, Metamod:Source, Psychostats, Sourcemod. The file manager panel lets you edit all the files through the panel, and gives you your FTP information. You can also schedule wipes and backups of the server there. The server control tab lets you start/stop the server, etc.
Compared to GameServers this is really extensive. I'm very impressed by the service. They advertise that they have "no support" but their panel actually is more advanced than GameServers. So far based on my experience it's far and above GameServers' service, and it's cheaper. However, you won't get support for messed up mods. This isn't a problem for me