It's quite unstable and most of the stuff isn't working
After Samsung Galaxy S II, HTC Hero and a few other Android smartphones, the next device to receive an Ice Cream Sandwich port is the Sony Ericsson Xperia X10.The folks over XDA Forum are doing a great job and are trying to bring as many phones to the latest version of Android.
Although this is just the first Alpha release of the Ice Cream Sandwich ROM for Xperia X10 and most of the features do not work, the developer team promises to catch up and improve it with additional fixes within the next weeks.
It is also worth mentioning that this ROM is a very early build, so those who are tempted to flash this release should know that only a few things will work after installations such as the in-call sound (mp3 and ringtones leads to WLOD), as well as Blueototh and GPS.
Wi-Fi and mobile data along with the rest of the stuff are a no go for the moment, but will probably be fixed in future releases.