Just had my first pop-up when launching Visual Studio about Reflector being out-of-date. I wasn't too crazy about the experience of this as it is disconnected from the primary UX of Visual Studio. I would much rather see it either be a notice when the actual Reflector UI launches or use the VS Extension Manager which notifies via a tray icon.
The whole update experience of taking me to a download page rather than having a self-updating option is up for debate as well. Personally I don't mind installing an MSI package that puts everything in its right place. I like, for example, the balance Telerik has struck in offering both automated (Windows Installer) and manual (zip file) installation options.