I am getting about 3 - 4 days of average usage out of a 100 % charge, running MIUI 1.8.19. I will continue to update this thread with confirmed findings of MIUI users posted here. Other than that, happy flashing! 
People experiencing battery drain issues please post the following:
My recommendations on increasing battery life:
People experiencing battery drain issues please post the following:
- Your running kernel (bmarko@magellan if you didn't flash anything on top)
- CPU spy screenshot of a drain (from 100 % to like 20%, you can get CPU spy from market)
- Screenshot of stats from the battery monitor in settings
- Did you perform a battery recalibration after flash? (Charging the phone to 100 % in off mode, then boot)
My recommendations on increasing battery life:
- Keep data on off whenever you don't use it. WiFi does not seem to have battery drain issues, use that instead if you are at home.
- Disable albumart and lyrics download in music player, when you dont use it.
- The media server can go crazy on battery drain - Even if you don't listen that much to music.
- Use another launcher than the standard one. Sometimes in rare occations (happened for me twice though) the launcher keeps the phone out of deep sleep. I have had good results with Go Launcher.