I actually really enjoyed 3rd year. It came after a long, brutal second year followed by step1. Were there stressful moments in 3rd year? Sure, I hated shelfs, but that's more 1st/2nd year like than clinical.
Third year has a lot of 1st times... 1st time you catch a baby. 1st time you suture a laceration on a drunk person in the ER. 1st time you scrube an operative case, start an IV, do CPR, the list goes on. Sure, towards the end of it, the student role gets old. But, since you're always doing new things, it stays fun.
I really disliked 4th year. Don't get me wrong, the free time was great, but that was a bad way to spend 45k. If I borrowed that money for a TRUE vaccation, I would have had a much better time. Also, as a 4th year, you're doing a lot of the same stuff you did as a 3rd year (more surgery, more medicine, with a couple of unique electives). Nonetheless, the student role had gotten really old for me. I hated interns acting like they were boss (come on, we're 1 year a part for crying out loud). I especially hated my notes/orders not counting for anything. I am ready to be done, and seem to spend all my time on rotations day dreaming of graduation.
For those who liked 1st/2nd year better than 3rd, you really may have made a wrong career choice. Sure the unpredictability sucks, but nothing sucks more than spending the majority of your time studying!