The competitiveness of the rotation is going to depend on the competitiveness of the program (which usually corresponds to the competitiveness of the residency). General Surgery often has enough spots so that acceptance for aways is not that challenging.
But there is no good answer without knowing your status and your destination choice. If you are 50th percentile in your class and a 202 on Step1, you wont go to Hopkins or UW, and will be hard pressed to find a worth-while away. Whereas if you were 80th percentile and a 252 on Step 1, you can pretty much apply to 4 aways and get two (probably ending up turning down a third), even if you wanted to go to Brigham, UCSF, and Stanford.
In general, the more "name brand" the program, the harder it is to get into. The better the residency is perceived (again, typically more name brands), the more competitive it is.
That being said, I can give you an anecdote. 80th percentile, 262 got 3 options for Uro at prestigious places, turned down 2. This is not me, but shows you how potent grades and step scores are for securing a desired away.
