I successfully ran some upgrades of a couple of very large windows applications through the upgrade wizard included in the 2003 version. It was successful :-) This was actually to my shock, since the previous version flat out crashed when upgrading one of the projects. For some reason, one of the component vendors products was in no way compatible with the 2002 version; even their samples would cause VS.NET to exit without any message. Also, after looking at the code produced, the upgrade wizard has gained a few additional smarts... but, it's still not a 100% conversion tool (and not advertised as such).
When converting one of the projects; I was able to actually have it up and running within about two hours. This project contains about 35 seperate code modules; uses API's extensively, interacts with IE's FTP engine, and communicates via TCP/IP broadcast messaging and IPX... so by no means is it a simple run of the mill application. The TODO items have also been improved a bit.
So, if you've had bad luck in the past; give the new version a shot. Again, I'm not saying it will convert all of the code; but overall, it's a significant improvement.
(NOTE: I'm not planning on releasing the applications; rather I'm mainly interested in harvesting some of the code to build as components for future projects -- eventually replacing the existing VB6 projects... I'm not that insane ;-) But it is nice to know that the conversion tool has improved this much. For some projects (especially class libraries); the conversion may be all you need to do to move your existing VB6 code to VB.NET.)