I've found that it is most often the plug on the easily replaceable cord that breaks, which I gather is by design and an improvement over mini-USB, where it was the socket that tended to break.
The biggest issue I've had with micro-USB is that pocket crud and lint tends to gather in the socket, but it's very easy to pick out with one of those slim plastic toothpicks or a similar tool. Every device I've had where the USB socket became wonky, a bit of cleaning cleared it right up.
I haven't encountered a single mini-USB port that I couldn't use with any mini-USB cable (however, these are mostly devices that I don't use as often as a phone, so my view may be biased).
Micro-USB ports, on the other hand, just stop holding connectors, even after I cleaned the port.
The springs that hold the micro-USB connector in are on the connector itself. I have one cable that barely holds on to my phone, but brand new ones lock in tight.
If a micro-USB port doesn't seem to hold anymore, I would replace the cable first.
The biggest issue I've had with micro-USB is that pocket crud and lint tends to gather in the socket, but it's very easy to pick out with one of those slim plastic toothpicks or a similar tool. Every device I've had where the USB socket became wonky, a bit of cleaning cleared it right up.