After doing some research, I purchased this phone from Amazon and I wasn't disappointed. This is an excellent, full-featured phone for the price and the first review quite frankly says it all.
I did have a slight problem when trying to download the mobile network settings for Vodafone during the initial setup process. Instead of automatically downloading the settings from Sony Ericsson, it would just hang for eternity on the download screen. After further investigation, it was found that there was a slight bug with the built-in software and an upgrade was available (New Build Number: 4.0.2.A.0.42) to overcome this issue.
When you buy the phone, you can avoid this problem during the initial setup (if you experience it) by simply skipping downloading your mobile network settings for your network. Once you've completed the initial setup, just go into the menu screen and select Settings -> Sony Ericsson -> Internet Settings and follow the instructions to automatically download your mobile network settings. When you get a bit of time, make sure you update your phone's software to the latest version so that this bug is eliminated.
Apart from the above, I would highly recommend this phone, especially given its impressive features, build quality plus the 2-year warranty. The only negative I would give is it could have done with more RAM than the 512MB that's installed plus with the majority of apps having a tendency of using only the onboard storage instead of the SD Card, the phone should have had more than 1GB of onboard storage installed. Mind you, I suppose Sony Ericsson couldn't have fitted any more into this phone, given how slim it is :)
If you're looking for a reasonably priced, quality and feature-packed SIM Free (any network) Smartphone, then the Sony Ericsson Experia Arc S is the one to choose.