This particular one isn't a problem for regular folks, because they don't know about the WinRT API.
I'm talking about all of the terms and branding not just WinRT. They were cleaver enough to come up with Metro. Why not something better than Windows 8 Store App?
RE: Windows RT/WinRT I see both of these terms used interchangeably. For the user it doesn't matter but the differentiations of Windows 8 vs. Windows 8 RT is a concern. I wish they would have called it something like Windows 8 Tablet or something that distinguished better from the Intel version.
There are lots of pieces that are "better than". The whole idea of Charms and inter-app sharing and searching. Live tiles on the start screen. Picture password (the feature my wife enjoys showing off the most).
Android has both a search and share feature that I'm sure the latter was the basis for W8's share. There's no advantage in W8 as the knuckleheads didn't extend it to the desktop.
Live tiles are a hot mess. It's hard to distinguish one from another as many use photos for the time and do not include a clear icon or name on the tile. Furthermore when your screen changes resolution (i.e. when you dock you tablet and use and external display) the tiles all get shifted and the landmarks you relied on are lost. They learned nothing from the issue of icons on the desktop and changing resolutions; another opportunity lost.
Picture password makes for great commercials but like most Christmas presents it becomes unappreciated quickly.
The apps will come in time. Windows is too big for devs to ignore, and the API is super easy to use.
I don't think you're going to see a lot of desktop productivity apps "re-imagined" as Windows 8 Store Apps because the Windows 8 Store App environment isn't productive.
And I really haven't seen any performance issues. Granted, she's not playing 3D shooters, but that's not really a tablet's target market.
Try Office. It sucks and is the one differentiator that WinRT actually offers.