In my humble opinion I don’t think that web 2.0 is dangerous. I think that the designers and programmers can be dangerous implementing web 2.0 features.

And I say this because sometimes giving some fancy “partial refresh” in a website demands the use of AJAX. This adds quite a lot of complexity and you need to be really skilled on this technologies to enhance usability at the same time that you make a better GUI. It’s quite difficult to achieve what Gmail or Flickr did in their Ajax implementations.

Nielsen, in his article “Web 2.0 can be dangerous“, points out that in their latest e-commerce sites tested they found out a lot of problems with Ajax implementations. Mainly because there are small changes like adding an item to the cart that are done Ajax style, like refreshing a small part of the page, and sometimes the user is not aware of this. AJAX is great, but you need to use it very wisely and you need to know the user limitations and be aware of the browser they are using. I did not implement many Ajax in my own websites, but I’m used to browse the web a lot, and regarding Ajax I’m aware that :

• Small changes and partial refreshs: They are not seen, unless you do it in a noticiable way the user may not notice. Remember you are playing the browsers music and it’s not an static application
• Check the scrollbar position before doing changing dynamically a header element!
• Cross-browser is a Must, as you add more javascript, more chances that sometimes fail in some browser
• Increase the speed, but make the code clean and small, because speed is always a important fact even in ADSL times
• All this checks add complexity to a website and in some cases even making things faster for the user the usability level is downgraded, a part of incrementing exponentially the production costs of the development team.
• My advice: Use Ajax wisely! . You don’t need Ajax everywhere just because it’s HIP and web 2. Many important sites as ebay don’t use it at all…and they know why!

The web 2 examples I like and they are really using this technology wisely are Youtube, Flickr, Facebook and Netvibes.-