I started in cellular in the late 1980s. The analog, one-frequency-per-call system was MUCH better than cellular phones of today. The analog cellular system we put customers on had 3 times the bandwidth as they allowed for the upcoming digital system calls. You could easily confirm this on an RF spectrum analyzer.
When we were told to give customers free digital phones for beta testing, many were angered by how poor the quality had become as they ran their businesses from them. They demanded their old phones be returned (reinstalled, since they were mostly car phones), but I was told by my boss to assure them the software upgrades would improve the service in the future (which I believed). From what I've seen, they never did.
I'd bet it's even worse now due to the sheer quantity of users and the multitude of different services bouncing between the air, antennas, and equipment. Think about it, if they need more bandwidth at a certain tower, it's probably not hard to dynamically take some bits away from the voice channels.