Reasons why your app is Low Rated!

Your app is a Mobile Phone app

1- Mobile in general has some constraints:

For each constraint, it may cause your user some difficulties when dealing with your app.These are some examples of how the violation of that constraint may manifest itself in a user review. Note that these are all highly context dependent.

Finite Data and Battery: ( battery & internet can vanish after sometime of usage )
"...completely drained my battery"
"...used too much data"

Divided Attention: ( mobile user has so much to do with other apps & with his life "while walking on the street, driving a car )
"...really hard to use"
"...too many notifications"

Handedness: ( Mobile Phone Life Style, 50% with mobile usage happens with single hand )
"...just wasn't fun to use" (this one is highly context dependent)
"...unitintuitive..."

Small Screen: ( You have a limited width & height, don't waste a space for an un useful functions )
"...terrible UI!"
"...too much on the screen"
"...tiny buttons"

Apply yourself: Take a randomly rated app on the PlayStore, Check the reviews,Read the entire review to understand whether the user is upset about a violated constraint.

from the"UX for mobile developers"
To be continued...