There is nothing wrong with a 243 for Deer
The 243 used to be the recommended starter rifle caliber for Deer Hunting. It is easy to shoot and doesn't really have any recoil to be concerned with. There are calibers that hit alot harder and are also capable of taking game larger than Deer. If Deer is all that's on your agenda a 243 should do fine. I don't own one but the friends that hunt with them selected the top weighted loads in 243. I believe that the recommended Deer loads are 100gr or 105gr. If you are looking at buying this rifle you may want to consider other calibers like the .260 Rem, 7mm-08, .308 Win, .270 Win, or 30-06. Deer are not that hard to kill. Bullet placement is always the most important thing, and a 243 makes it easy to put it in the right place. Some of the Hunters on this forum use the 243, and I am sure they will offer their opinions.