> Most espresso shots end up being sour and unpleasant for me
Most are, even in cafes. I didn't realize this at first, and I bought an espresso machine to be more convenient than starbucks. But, it took me at least 2 months of owning an espresso machine before I was able to get the grind, tamp, extraction temperature and extraction time right to pull a good shot consistently. Honestly, it was two months of pain. But, it's been heaven ever since.
I don't mean to be a snob about it, but I used to enjoy starbucks espresso drinks -- not as much anymore. They're slightly bitter or sour most of the time, and once in awhile they're completely undrinkable. I live between two starbucks and I travel a lot, so it's not like it's just one bad location. I still go to starbucks once in awhile, but only if it's for a social reason... not for the coffee. My wife was not convinced at first, but now she agrees that my lattes are better and more consistent than Starbucks.
I think anyone who likes coffee will have the same reaction as you... their mind will be blown when they have a proper shot of espresso and they will probably hate it until that time. So, if you enjoyed it more than coffee, you could take the plunge too. It's like a lot of things though, if you want to do it right you often have to do it yourself.