Official Google Mobile Blog: We're open for business
I use Google's mobile version of the services I use on my desktop daily and these are my primary complaints:
Google Calendar: why can't I run a search on my appointments?
Google Documents: spreadsheets are hell to work with as HTMLs, the one time I tried to download the xls I got an error 500 message and gave up since the data I needed was deep into the document.
Google Reader: this is by far the most useful mobile online app, but all I can do is read, star it and mark items as read. Once it's marked as read it's gone forever, so mark wisely. Litefeeds has some nice functionality, it let's you even tag a post on del.icio.us, but I didn't like the feel of the mobile java app, it needs some polishing.
Maybe there are workarounds for this complaints I'm sharing, but trying to figure it out on a mobile device is something complicated. Even google groups is out of reach to lend a hand.