Thanks to everyone for being patient yesterday and then jumping on the download as soon as it became available. There is a common theme in the early comments, yes, 512MB RAM on a Windows Vista UMPC is not an optimal experience. We did a lot of performance tweaks during development and really tried to squeeze out what we could, in fact at one point we stopped feature development and just concentrated on performance for two weeks.
We expect new Windows Vista UMPCs to come with 1GB RAM (or at least have it as an option). I have a Q1b as my personal machine and with 1GB response times are quite good. My personal experience is that the RAM makes a bigger difference than CPU.
Also, our testing showed that hard drive activity can have a big impact on responsiveness. I generally turn off the search indexer on my UMPC. I love it on my desktop but it just overwhelms my Q1 when it kicks in.
Keep the reviews and feedback coming!