As subject I guess.
We currently push it via GPO but let people choose.
I'm debating whether it would be sensible to set it as the default but use the Chrome admin tools to keep a whitelist of stuff that should be opened in Internet Explorer.
Now I know that every browser has its fair share of issues so I don't really want this to turn into one of those threads where it's about religion, I'm interested in technical/compatibility issues or if your users just plain didn't get on with it etc.