Third year is very interesting. You spend the two years previous cramming in a bunch of facts about obscure diseases that seem like they have no relationship to real life, then in third year you meet patients and see that these diseases actually exist, and you find out that you might actually be able to use this knowledge to help people.
You also learn skills such as blood draws, reading EKG and X-rays, tapping lungs and spinal fluid, taking histories and physicals. It's a huge step up from previous years. You meet a lot of very interesting people - physicians, nurses, patients, secretaries, all who seem a little crazy from spending too much time in the hospital... 🙂
It also means more work (at least for me). The first two years were pretty slack - I cut most of my classes, and studied at home 3-4 hours a day. That's all. Now I go to the hospital 8-3 or 8-4 M-F (I study in Israel, so I have an easier schedule than they do in the states. No scut work!), and take call usually once a week until 10 pm or so.