What are downsides of using web technologies for desktop applications?

An equivalence would be, what are upsides of using native technologies for web applications, where you may have a remote server, anyway?

Comments

[Alex Lohr]

• UI may be consistent with your app on other systems, but not with the system itself.
• Performance and/or efficiency might suffer
• Might require ugly workarounds for a hybrid approach that includes native technologies (and/or mix of languages, which can drive up the cost of development)