App reviews and ratings are extremely important to the success of your app marketing efforts. Successful app developers understand this and use it to their advantage.
Here are 3 reasons you should really care about app reviews.

1. Users are judgemental about your star rating

At ASOBarcamp 2 Thomas Petit summed it up well in one diagram.

Unless your app is at least 4 stars (preferably 4.5 or 5 stars) then users view your app as rubbish.
Users are significantly more likely to download your app if you have a high rating.

2. App reviews & ratings have a big impact on rank

Reviews and ratings are a very strong signal for us on Google Play – Ankit Jain, Google Play
Moz studied the factors of ranking and came up with the formula:
Ranking = fn(Rating, Rating Count, Installs, Trends)
Weight of factors in the Apple App Store ranking algorithm :
Rating Count > Installs > Trends > Rating
Weight of factors in the Google Play ranking algorithm :
Rating Count > Installs > Rating > Trends
Fiksu shared some really interesting data around what happened when ranks and reviews were introduced as a weighting.

After the algorithm changes apps with ratings, 4+ stars received a ranking boost. Apps rated under three stars dropped down in the charts. Mid-rated apps of 3 to 4 stars settled to middle ranks.

3. You are much more likely to be featured with a high rating

We dug into the top charts on iOS and found interesting results.

Over 50% of apps featured by Apple had a 4.5 star or higher rating. 75% of apps have at least a 4 star rating.

Reviews & App Marketing

App reviews and ratings are critical to user perception, ranking and your chances of being featured. These are arguably the three most important factors in the success of your app.