Different strokes for different folks, I guess. I can't stand using a webapp for something that should be a desktop app. I just don't get the responsiveness I need. It's like using Photoshop without a mouse.
I had that experience a few years ago, when javascript execution engines where not optimized yet for speed. Today, I have the same experience with apps built using flash, where there is an annoying delay when hovering/clicking. A mature webapp running on a fast javascript engine does not give me any noticable delay. The "feel" is just the same as a native app.