how secure is a VPN

[Steven]

I have setup various VPN links using a variety of routers and
configurations, and always been under the assumption that they are fairly
well secured if setup correctly.   Now I understand that the level of
security will differ depending on your particular setup.  However I guy I
know who runs a rather large ISP claims that under the current SA
infrastructure VPN's are simply not secure at all.

 

Does anybody have any thoughts on this, am I blissfully unaware, is there
some truth behind this?

 

Thanks

Steven