The SECOND ics update Contains a few bugs and you are better off staying on build number 4.1.A.0.562, or even with gingerbread.
There is the led notification bug where the sms light wont blink if your screen is turned off. This is all over the place in sony's forum.
Another one is the media storage bug, discussed here
Music player not updating songs list after ICS
I had this problem after updated to 4.0.4
I believe this is a bug because i have since reverted to 4.0.3, and have not experienced this problem anymore. I do not have to clear media storage data to get my music player refreshed.
Of course, in the process of downgrading using flashtool, it is said that i have voided warranty, but in any case...my phone is st18a, north american version, but flashing the st18i firmware seems to work fine so far
The first update is the best though...there is absolutely no point in upgrading to 4.0.4 in my opinion
Lesson learned for kauvio