in my experience system.windows.forms is a story of it's own.
1. There are very few controls provided by the framework (try to implement office 2003 alike application in .Net)
2. Eexisting controls are inflexible (windows.forms.datagrid is much more rigid than system.web.ui.webcontrols.datagrid)
3. Databinding throws internal errors all the time e.g.:
"CurrentCell cannot be set at this time. Moving your code to FormLoad should solve this problem"
"Specified argument was out of the range of valid values."
"Index was outside the bounds of the array"
4. Reporting... yikes!
I've worked on two ASP.Net project before and now I've been working on a client-server (desktop) application. .Net is briliant on the web. But i guess someone said "OK, we'll provide system.windows.forms, just to be there. Noone's gonna use it these days, anyway"