If you’re developing a web portal, then definitely you should consider using portlet technology. The confusion on the choice of portlet technology arises when:
you don’t know what are the features of a web portal (content aggregation, personalization, consolidated view of business, and so on). If you’re building a website which doesn’t aggregate content or allows personalization, then portlet technology is not for your website.
you think portlet technology is rocket science. Infact, portlet technology is an extension of servlet and if you know servlets, you’ll find portlet technology quite intuitive. It’s not very simple, but its definitely not rocket science.
you think that you can’t create portlets that use AJAX or Comet (or reverse AJAX). The example in chapter 12 of Portlets in Action book shows that portlet technology is mature enough to easily help create portlets which make use of AJAX or Comet.
you think content aggregation can be achieved using servlets. Imagine using servlets to aggregate content from different data sources and ensuring that when you refresh content of one data source, then the content retrieved from another data source is not fetched again. Now, also imagine how your design will look like using servlets. Is it maintainable ? extensible ?
you consider inter-portlet communication isn’t that useful. Well, think of a real business scenario where you aggregate content from different data sources and you want the content to change based on selections made by the user. Now, imagine developing a web page using servlets to change content of one data source based on actions taken by user on the content displayed from another data source. Again, imagine how your design will look like using servlets. Is it maintainable? extensible?
you consider personalization can be achieved using servlets. You need to think about the data structure that you’ll use to save personalization data. At what time will you retrive personalization information from data store and when you should allow it to be saved?
you consider portlets as just UI components. Portlets are like services and not UI components.
portlet technology is only fit for the first page of your portal. You’re possibly not using the portlet technology to the full-potential if you just end up using portlets on the first page of you portal.
you consider portlets are replacement to web apps. Portlets complement web apps and are not meant to replace them. Have a look at www.igoogle to see how portlets and web apps co-exist and complement each other.