I don't know about unicorns, but ice cream sounds good.
The problem with the first three years is that you are trying to accomplish 2 things:
1) Learning information / skills to become a good/great doctor.
2) Learning information / skills to succeed in school (grades, boards, etc.)
Ideally these 2 points should be one in the same. Unfortunately, this is usually not the case for many schools and students. Striving for both of these goals is exhausting and on occasion partially exclusive. The great thing about 4th year is that after August your grades don't matter anymore (obviously you still have to pass). From this point on, your sole goal is to add to your doctoring skills, not to get the Honors or A.
Third year has a lot of clinical time and a lot of didactic time, whereas 4th year is mostly clinical time. This makes you feel like you are really in the thick of patient care.
The best parts:
1) Vacation time: I have 3 months off during my senior year: December & January as well as this coming April. December and January was spent interviewing for residencies and preparing for step 2 boards, but there was still a lot of time off. April is just for me, then I coast into May graduation (it is going to be a glorious April).
2) Free weekends: Of the 7 remaining months of rotations I had to do, only 2 had any weekend requirements. And one of these months was in my chosen specialty, so it was still an awesome experience.
It is definitely a needed respite between medical school and intern year, but at the same time I am excited to get residency rolling.
Hope this helps.
-senior medical student / Future Emergency Medicine Resident