I'm strongly considering it, its kinda between this, the Motoroi, and the HTC Desire.
The potential problems with this phone is that its Android 1.6, and with a custom UI courtesy of Sony. Sony's forays into the smartphone realm have hardly been illustrious so far for the most part, and in particular the stability of the software they've delivered has been poor, which is a strike against this phone running on Android 1.6 and therefore relying heavily on Sony's software customisation.
I'm thinking I won't buy it at first release, which is what I tend to do with new phones, but wait a little for the reviews to come in and make a choice then.
i was worried as well but the latest showing of it has totally turned me around, perfoamce of the time and media scape apps is where it needs to be now, and sony have said there is def a andriod update to 2.1 on the way.
couple of recent vids, google search will show more if you sort by renect ones.
kinda know sony wont be counted on updating past the promised upgrade, and the dev comunity might have probs hancking roms on it it with thr UX intact ... but yeh ..time scape i really like the looks of ... better than winmo7's all in place implementation of having data for a particular person at yr fingertips.
and the screen, and the cam ... hmm. keen on final reviews and battery performance with timescape used as the default homescreen.
I wouldn't even trust them to deliver the update to 2.1 to be honest, and I certainly would not factor that promise into any decision to buy the phone. Its either good enough to get without it, or not at all. The reason being that they promised the Windows Mobile 6.5 for their previous flagship X1, and it never materialised, so even their official statement is not particularly trustworthy.
I've seen the videos, speed-wise Time/Mediascape seem pretty decent now, but who knows how stable the phone is overall. The Satio has been withdrawn from the market twice now due to major problems with telephony functions, so we'll see.
I'll be interested to see the cam, should be the best Android one out there by a long shot, if the Vivaz 8mp shots are anything to go by (the samples I've seen from the X10 are not so convincing yet, pretty, but lacking in resolved detail rather substantially).