InfoPath web-enabled forms are extremely useful, and are one of the features helping MOSS enter new industries. These forms are rendered such that a variety of web browsers (not just IE) can use and view the forms. This is powerful because you can now create forms which have a specific look and feel including limited custom code to display and capture information. For companies with legacy systems such as Lotus Notes, this opens new doors where they can use InfoPath forms to move their Notes applications into. Now, this isn't what I would advise, but it does open that door if it is a strict requirement. Having said that, there are many limitations to web-enabled forms. I was quite surprised to find how limited as well. Understanding the technology behind InfoPath helped me understand why those limitations were there, and how to find some workarounds (I will share these as I can in future posts). InfoPath is based on Xml and Xsl. Thus, the presentation has to be handled by Xsl which is why it has many limitations. I can't go into the technology specifics, but there are many Xsl and Xml tutorials out there. I have to say it did make me feel a little more at peace to know that (I was quite annoyed by the limitations). It still don't make me love web-enabled InfoPath forms, but I know how to work with them and achieve the behaviors I need.
For a complete list of the features supported by InfoPath web-enabled forms go to http://office.microsoft.com/en-us/infopath/HA102040851033.aspx.