Blackberry were flaky even in their heyday. Problems abound with things like phones suddenly switching to BES mode, BIS losing settings for an account because it's got to get a new 'service book' sent. These were all blackberry-invented annoyances that were meant to keep a legacy requirement, namely email, running 'reliably'. Small businesses couldn't afford a 'blackberry server' and in any case with email services moving into the cloud, having your own email server seemed a bit of a nonsense.
Blackberry's issues were that they were trying to solve a problem that didn't need to be solved. And the thing people really wanted, which was access to websites, really didn't work very well at all on blackberries. As for the quality of the apps, they were abysmal. I had never found a blackberry app that actually looked good.
What's interesting is that the blackberry messenger became so popular. What killed it was that they were so late releasing their BBM client for android and ios. I seem to remember it was announced and then months later, it finally became available. Too late. People had moved on.
It's ironic that blackberries were aimed at the corporate market and that they became so popular with kids - mainly because of the BBM.