If you are pursuing MBBS from India, you have to face a 6 months back ie you fall behind 6 months from the current batch and prepare and give your anat, physio and bioC papers again. 

If you are talking emotionally, well, it comes with it's  hardships. Like not being able to hang out with your friends because of different exam dates, missing the class elections etc. But the major drawbacks are :

Diminished self esteem- this of course makes you wonder about your worth, decisions, other options of career ( every person thinks of that in MBBS when they hit rock bottom ). You start doubting yourself at so many levels.

Company - you are among people who might have very less to do with studies. They are always with you, during classes, break, even become your hostel besties. That's bad because people around us influence us, their ideas, thoughts have a great impact on out thinking. 

AIPGEE- you might not be able to give the PG exam at the same time as your friends.

All that aside, i have seen and heard that a few among the back batch are the best doctors to graduate and do far better than any of regulars. That's a simple case of mindset, once you have hit the bottomline, you realise the imp of jumping back and work harder than ever. Later in life you actually thank this situation for turning you around. 

So all in all, you become what you think. What happens to you is your reaction and in medical, your patience and patients teach you more than books. So keep learning :)