I am using zenfone for about 4 years till now there is no problem.But it is well known with its heating problem and battery capacity, they made mistake in choosing right amount battery backup, it has only 2100 Mah. this much capacity doesnt support the working of its processor and 2 gb ram.
Today one of the main problem is the battery backup, I need to carry a powerbank while travelling a long trip. So I recommend Zenfone max in this price range if you are a ASUS lover, it provides battery capacity of 4100 Mah. I think that would be better.
PROS
1] No hanging set - After 4 years of usage it didnt hang even a second
2] Support all hd game
3] Easily manage multi tasking
4] OTG Support
CONS
1] Heating problem- if you play hd game even for 30 mins it start heating like a iron box:p
2] Insufficient battery capacity
3] Dont support 4G
4] Hard to find cases and backcover