I' ve shot a .243 and a .30-06 and have had no problems with either, recoil-wise. Deer shot went down within a few feet of the position at where they were shot, whether it be with Remington CoreLokts, Sierra GameKings, Nosler Partitions or Winchester FailSafes(in the .30-06) and others I don' t remember and at distances from 25 to 150 yards. For me the issue has been precise placement; I' ve been most fortunate that the deer were in broadside positions.

To get back to the original question, yes, the .243 Win is ok for deer, with proper presentation, bullet placement, decent bullets and adequate range practice.