I'm on BE at the moment mate, I moved from VM adsl ( worst service ever ) and I can honestly say its sweet, no restrictions that i've come across so far and i'm getting 14meg download speeds for 18 quid a month, so far i'm very happy with the service. If you need to check who you could connect to go here
http://www.samknows.com/broadband/checker2.php
That'll tell you who you what kind of services you can expect, to get the BE up to 24meg it'll need to show you O2/BE LLU on your exchange, if it is then you're laughing, and if you want to leave VM cos you're not happy with the service complain to the ISPA, its an online form and somebody from VM aftercare dept will contact you within a few days, when I spoke to them they were really good and do listen to what you've got to say.
http://www.ispa.org.uk/
Best of luck mate