The good: smartest people I have ever worked with, though also some of the dumbest (think of a saddle curve rather than a bell curve :-). Really interesting, fun, and really super-hard technical problems.

Discouraging-but-part-of-life issues: nobody is in a rush because everything is a marathon. It typically takes decades to get anything into the market; though regulators over the past few decades have been changing things to speed things up (basically doing science to make the process more adaptive and dynamic) it's still hard. You're continually looking for needles in haystacks: wispy signals that may be noise, extracted from huge datasets. As a startup, expensive slow, e.g. an overnight session on an HPLC can be a $10,000 experiment (or more because you're probably running a lot of those instruments in parallel at once) after having a bunch of people working all day to prep the samples.

The terrible: the industry is riven top to bottom with fear. Fear that the science will not work out. Fear that someone else is smarter than you (as a result: pervasive arrogance and hostility). Fear in the FDA that some company trying to game the system* will get something past you, or that the inspector general will launch an investigation, or some congressperson will launch a missile at you for no legitimate reason.

Also, you're launching artillery shells that can't be altered in flight. You write a study and then you have to run it with the protocol you wrote and got approved. You can't alter your marketing message unless it refers to scientific results explicitly demonstrated in a trial. And since the trials typically take years, there's a lot of sitting around.

* Back when I was in the biz we absolutely did not try to game the system and it made it a lot easier to work with the Agency (FDA). But the rules kept being made tighter and tighter to lock our bad action by companies. And of course the recent destruction of the FDA means all the rules have been thrown out the window, but by then I was already long gone. But my friends in the industry are still shocked and appalled.