Some of the whole Web 2.0 thing is great - the social media/networking part.. A lot of simply sucks. The fundamental flaw for me is assuming that people will want to or are able to do everything online.
It might work for the geeks and techno early adopters but out in the real world it ain't going to happen anytime soon. This Techcrunch post about 14Dayz helped highlight it for me. $99 for an online time tracking app! Why would I pay that much for something I can use only some of the time?
Most of us don't live in a world where you have constant internet access. Wifi hotspots still only cover a tiny part of the world and cost far too much.
It's the same for a lot of these cool looking Web 2.0 apps such as Writely, 30boxes and voo2do. If they only work when you are online then they don't work! I want to be able to work when I'm in the park, on a train, in a cafe or at a meeting.
What does work are desktop apps that can be synchronized over the net. It's great to be able to access my calendar, to-do lists, contacts, email, documents etc on the net from any PC but it's more important to be able to work where I want, when I want, on what I want.
For most people in most places web-based apps won't do that for many years to come. The future for me is web-aware desktop (and palmtop) apps.
NOTE: These are my personal views and not necessarily the views of Softalk.