The problem with zf2 MM starts from many aspects, battery drain is the main one. It just drains too fast, 100 to 90 in a blink, when using LP can go almost twice the time.
I have to admit, many bad reviews, but the cause is not unknown: using heavy load tasks while using 9v fast charging. 80% chance u will damage the touchscreen and lcd.
No smartphone will survive 4 years, let alone the battery it self. Phones with fast charger have shorter lifespan. I predict this phone can go up to 2 years more max. Unless they kill Lollipop this year. Then bye bye zf2. MM really kills this phone. Trust my words.