Given what a DNS does (not going to detail that here) it is likely to go either way in fixing a problem or creating a problem.
For example, many ISP's have their DNS respond to pop3.email.com for the email they offer you. Google and OPENDNS would not honor such use.
improve my connection?
I'm with AT&T DSL. Would switch to Google DSN effect my Firewall and security software? Would AT&T (or another ISP) have a problem with users switching to it?
Is anyone using this DNS service?