Flock was an interesting idea when it first came out. I remember the first excitement that people had when the first developers preview came out. The tide turned quickly. People wondered why this needed to be a different browser and not just a bunch of extension for FireFox.
I’ve seen two developers previews so far, flock and songbird. They both had the same problems. They were cool ideas but so early in development that people just complained about the bugs.
Flock stuck with it and their first beta is much more polished then the first version was. It’s integration with del.icio.us is great. How it integrates with photo services is the most dynamic and intuitive I have seen. The dynamic search is also interesting and with some more customization could be extremely useful.
If there was some way they could integrate with bloglines I think that might even push me over the edge to use Flock instead of FireFox. It even seems all the FireFox extensions will work in flock which is almost a requirement now for any browser I want to use.