I actually remember Precious Cargo for a distinct reason - it was the first episode of Enterprise that I did not watch all the way through first run. I was an exceedingly loyal ENT viewer up to that point, but I remember that night, about a quarter or a third of the way through the episode, I got up and worked on some school project or something - not even due the next day!
It's not that I think Precious Cargo is particularly awful, but I think I was feeling a serious slump in the middle of season 2. I simply found it thoroughly mediocre. It just felt like we had seen it all before, and better in most cases. It was the disappointing trend that I think got to me more than the particular episode. The straw that broke the camel's back, as it were.
It was just boring. Vanilla. Drab. Like a great deal of the Berman-era Trek (especially in the later years of Voyager.) I think it was especially disappointing to me as I found the idea of a prequel to TOS a fascinating proposition and the greatest opportunity the franchise had seen since TNG to really "shake it up" and add some color and liveliness. Instead, we were consistently getting episodes like these that could just as easily have been an episode of Voyager. It felt like I had to wait through tons of filler episodes like this to get to the good stuff, like the Earth-Romulan War or the birth of the Federation. Little did I know...