I have been working on a project that has 2 interfaces - windows forms and web. Over the past 8 months, we have faced more issues with maintenance of our web apps (works in IE not in FF, ajax breaks in some weird ways that is not easy to debug... ) and so on.
On the other hand, the winform app is easy to install. We have a xcopy version and click once deployment of it that allows the user to click on a link in the browser to download and install.When we upgrade the app all we need to do is to publish it on to the server and send an email with a link. When the user clicks on the download link ... they have a new version... all that is needed is the 2.0 runtime.
Is the tide now changing over to smart clients?
EDIT: Are the browsers now causing the problems with web apps (too many platforms.. not all of them following the same standards) that plagued the client apps?
EDIT: Web applications have to be tested on as many as 4 browsers (not to mention IE - IE 6, IE 7 and IE 8). Whereas smart clients run on top of the framework, so they dont need to be tested on all the OS's.
We had a PHP website for our intranet utility. We have switches since 2 years over a C# application with ClickOnce and everybody love to works with a desktop application. Update are done automaticly and the developement team have reduce to about 70% all GUI/Visual times. We might have this high level or success because most computer are pretty the same (all same OS and about all the same configuration) but well : success for us. Hope this experience give you some help to take your decision.