Im thiing of switching to vonage, as it will probably save me like £30 a month. Ive seen a few reviews out there, but none that seem legit...either people arent happy at all, or theyre too happy.

Ayone out there using it can give me a nice objective opinion?

I think you will just need to try them out.
They have a 30 day money back guarantee.

I was thinking of trying vonage but I already have my own SIP phone but they wont let me use it and have to use there adapter instead.

I have vonage and it just works, not sure what else to say really. however I only use it as a cheap way to keep my number when having moved house.

What I meant is that I've read horror stories of terrible call quality, service interruptions, lag, inability to provide duplex speaking.

If it sounds exactly like a regular phone, that's good enough for me. I'm sick of paying £13 for line rental plus £25 for calls to the states each month...

Yeh it really just works like a regular phone I even forget i am making calls through the internet, call quality is fine in that i did not question it so no worse than a normal landline. have had it since February. Not tried the duplex speaking. No disruptions at least when ive tried using it.