Also, check out the reviews and battery life for the sony 2-in-1 you posted. I'd rather have a surface-1 pro :)
I followed up on this, and the 4.5-5.5 hours I see across multiple reviews is not good.
On the other hand, the system starts at $699, while a Surface Pro with similar sized SSD is $999. A mediocre battery life might be acceptable at the lower price points, but it's certainly not if you intend to spend nearly a thousand dollars on your system.
Either way, the trend is still positive. Each new design seems to improve over the previous design - better pricing, better specs, better performance, etc. The Sony Tap series comes with a fairly high end display, with incredible brightness and color accuracy. You actually need to see it for yourself at Best Buy to fully appreciate it. I'd say it even rivals the iPad, and no doubt taxes the battery life with the modest sized 30 WHr battery.