Easy to work with, biodegradable, inexpensive, can be infused with different materials to introduce different properties; what’s not to like about PLA?

I like to use PLA. It’s a good filament for a variety of uses, and I use it for probably 80% of my prints. But it’s not a one-size-fits-all. I like to use it for a lot of proof-of concept ideas that I have had or to experiment with different versions of a component.

Some of the downsides of using PLA, you need to be careful of which manufacturer you purchase from. Not all PLA is created equal. Some manufacturers put in cheap additives to keep their costs down. Then these additives end up causing problems with your prints. Find a good brand, dial in your printer for that brand, and stick with it.

Compared to other materials, PLA has pretty poor thermal properties. It your component is going to be anywhere near any type of heat source, PLA may not be the right material for you.

PLA doesn’t hold up very well outdoors. 

PLA, has pretty poor hardness properties. 

As with so many things, it depends on what you are doing. For the right application PLA is great.