The vast majority of people are somewhere in the middle, I think. I was closer to Planes2Doc in my experience, though I will say things got better third year.
In general, I despised first year, felt marginally less miserable second year (because at least I thought path was reasonably cool), fell into a deep pit of despair studying for step 1, realized I at least still liked medicine in general as a third year, and was bored and depressed as a fourth year. It didn't help that I didn't really feel like I fit in with most of my classmates and generally felt like a bit of an outsider. Med school is a lot like high school. Socially, there are cliques and when you artificially create cliques out of a bunch of nerds (some of whom think they're cooler than the others, but are still nerds) weird dynamics emerge. The constant competition, whether you want it to or not, also gets in the way of having genuine friendships. At least for me this was one of the toughest aspects of it. I made a couple of close friends, but was annoyed at having to constantly be near a whole bunch of other people I couldn't stand.
I also felt like at my school at least there was this big culture of "never let them see you sweat". I don't think that was unique to my school by any means, and it's probably at least partially why there are so many depressed people in medicine- it's less about the workload, and more about the fact that if you're the one person who complains, you're seen as weak, a whiner, and obviously not as smart as the rest. I'm a complainer, undoubtedly, mostly because I find that it helps me deal with whatever is going on my head to express it and discuss it with other people who feel the same way I do. However, in med school I found myself in this culture of "everything is great! Everyone is happy! We're all so well balanced!". To this day I don't know if i just struggled more than my classmates or if they were just better at drinking the kool-aid, but i resented them in huge part because i felt like i was being judged for being the only one who wasn't super happy and whose life wasn't super balanced. Instead of the typical pre-med "well I studied ALL NIGHT and didnt sleep for 24 hours straight!" "oh yeah? Well I studied 36 hours and havent slept in days!!" fight, there was the "i studied, ran a marathon this weekend and then i went to the beach!" "oh yeah? Well i studied, did a triathlon, ate an all raw paleo diet, volunteered at the animal shelter and went shopping!" fight. Meanwhile I'd be sitting there being like...yeah I just studied, ordered domino's, and fell asleep on a book, am I just stupid?
Interestingly, third year was a little better cause I got to befriend the residents, who all admitted to not having a life and who were all pretty cranky. Now I can tell you that residency, from that perspective at least, is MUCH better and I'm WAY happier. We're all exhausted. We're all on the same boat. Even the differences between specialties aren't as bad (though the surgeons still argue they work harder than everyone else- and to be fair their hours really do suck). I feel way more comfortable with life now, even though I'm much busier and work much longer hours than I did in med school.