Unfortunately only a very few people post reviews on the App Store. Sadly this mostly happens if the app has failed for them for some reason and the result is a negative review. It would be good if users who like the app would spend a couple of minutes posting a positive review to help create a more balanced view of the situation.
If an app crashes then a crash report is generated and sent to the developer who can then analyse it and, hopefully, rectify matters and produce an update to fix it. I have received very few crash reports over the past few releases, and all have been fixed.
I would ask though, that if the app causes problems then please contact me via this website before posting a review. That way I will try my best to resolve the issue.