The Tolly Group released a report comparing the Network Access Control of Forescout, Bradford Networks, Cisco Systems and Juniper.   Disclaimer: Tolly performs paid research, and in this case is paid by Forescout.   Nevertheless, they do a good job comparing product.   You should just take it with a grain of salt.

http://tolly.com/Docdetail.aspx?Docnumber=212105

I’ve used Forescout for about four years.   I think there is an ease of deployment that is unmatched.   There is also a great flexibility in the type of rules you can apply.