1. I don't use inbuilt gallery so I can't judge.So a short review so far:
PROS:
1. ROM is good and stable.
2. RAM consumption is low..1.5-1.6 GB average
3. Noticed no major bug yet which can hinder it to work properly.
4. Battery backup is better them MIUI stock ROM.
5. Good for daily driver if you want a change.
CONS:
1. Sometimes the pics in gallery wont open even after clicking multiple time...you will have to click other pics randomly and then it starts working.
2. Network reception of my 4G is quite low..at the same place MIUI was much better...here it is almost nil...but still work.
3. I use modded google camera...which lags a lot....hell a lot..on MIUI it was smooth like cream.
4. Icon of all the app which are not installed from playstore won't show up. I mean, apps from unkown sources will get installed but their shortcut wont appear, don't know why. I made a work-around by installing app shortcut creator but if i reboot..all such icon will vanish again. (Any help would be appreciated)
5. system lags a bit sometimes.....takes time to open setting...n likewise
2. My 4G signal is strong.
3. Gcam - try another mod.
4. I have installed several non Google Play Store apps and all have own icon. Maybe you have to clear cache or install another launcher.
5. Slightly lags does not matters. You can change battery profile from Balanced to Quick.