Yes, I heard the same thing from a friend running it since last Fall... heck, when I tried X10 back in November it wasn't that bad already... and it's been 4+ months now, I'm sure they worked out all the kinks - as a matter of fact that was the official reason for postponing the launch date, to make it absolutely bug-free.
SE is top-notch when it comes to UI design, I always said it - it's just they have been always stretched too thin and never had the time to properly finish everything. It's a (resource) management issue and I think it is the same type confusion that caused the demise of Sony during the past decade.
SE should settle on ~2 platforms (plus their proprietary one for the integrated and lower-tier phones) and cut the number of concurrent models in half but every new release should be near flawless, as bug-free as literally possible because when you are asking $500-$1k for a phone it's better be perfect or you will lose its angry owner as a customer forever...
Xperia Z Ultra (64GB) & SE Xperia arc (2011-12, still live concert recorder)
[Xperia T (2012-2013) SE Xperia X10i 32GB (2010-11)->SE Satio 16GB (2009-10)->SE Xperia X1i 16GB (WM v6.5.3) (2008-09)->SE W960i 8GB (2007-08)->HTC TyTn (HERM200) 4GB w/ Cingular HSDPA (2006-07)->SE W950i 4GB (2006-07)->Sprint PPC-6700 Sprint WCDMA(2006)->Nokia 6620 w/ T-Mobile EDGE(2004)->Nokia 3650 w/ T-Mobile GPRS(2003)->Motorola V60 w/ VoiceStream WAP(2001)...]