"Hint: if people stick to your old interface rather than to migrate to the new and shiny one then they probably have their reasons. Forcing them is not going to make them happy." This leads to a dangerous line of thinking. There will always be a group of users who are resistant to change, and during a time of change they will be most vocal. If you listen to them you'll stagnate -- which is almost always the kiss-of-d…
Slower+buggy is not an improvement. I can't count the number of times that the new interface has reported 'twitter is over capacity', 'you have already tweeted that' (when it wasn't true) and a whole pile of other errors, if it worked at all. Page load times of several minutes on a 10 Mbit connection on a very fast machine are ridiculous. Of course you have to 'take risks to innovate'. But rolling out buggy and slow…
Therefore, "Slower+buggy is not an improvement," took a minute to parse.