I have visited both the Smithfield and Soho venues. I enjoyed it. It was £20 an hour (back then) but I think that was per bay rather than per person (I was on my own anyway). The shot detection seemed pretty accurate (certainly had my slice down to a 'T') but the big flaw/failing was the putting side of things which was a bit pants. That said, when I played, I just played tee-to-green and then skipped to the next hole (I wasn't that bothered about the putting anyway).
Each bay had a several racks of new TaylorMade equipment (with left and right handed, graphite and steel, ladies and mens variants) and the balls in the bay ranged from ProV1/ProV1x's to budget balls, so as an experience, pretty much everything was covered. One of the key things is the choice of course on offer: St Andrews, Royal Melbourne, Pinehurst #2, etc. Ok, now where near playing them for real but a decent facsimile (especially if you doubt you'll ever get to play the real thing in person).
There was mention of one of the future course upgrades being the hallowed acres of Augusta National. I don't know if they ever managed to procure those rights but with the likes of Tiger Woods 2012 now including The Masters venue, I hope so.
It was central London (where I was working away), mid February and the whole country was covered in snow, so any golf in a warm environment (and with a beer to hand) was welcome relief to the purgatory outside!