We've had Securus for several years and..
Yes the console is a bit amateurish, looks like it was designed in frontpage It's not the most intuitive but we've never had any problems with it's functionality.
The price is worth it IMHO, we have lot's of situations where students are using computers without supervision and although it isn't fool proof it provides an extra layer of protection. Once a few students have been dragged in to see the head of ICT for a roasting at the beginning of term the word gets round and the number of violations drops right off.