Pros:
(1) more than adequate killing power, (2) appropriate loadings commonly available everywhere, (3) appropriate types of rifles commonly chambered in .30-06
Cons:
(1) trajectory may limit shooting to less than 300 yards, (2) recoil more than what other adequate cartridges generate (.25-06, .243 for example).
I'm trying to be objective. It is hard to argue with my pros, so I'll let them stand unsupported. With reference to trajectory, the .30-06 does not have as flat a trajectory as other available cartridges, for example the .25-06 and the .243. Sure, you might be able to theoretically kill a deer with a .30-06 at 1000 yards . . . but you might also need to be a champion rifle shooter able to estimate range to target with extreme precision. Also, while the recoil of the .30-06 is manageable by most hunters, notwithstanding it delivers more recoil than other adequate cartridges.
I've got two .30-06 and I appreciate them greatly. I also have a .25-06 and a .243. I take the .25-06 or the .243 for deer and pronghorn hunting and take the .30-06 for elk hunting. Sure, I could use the .30-06 for deer and pronghorn hunting also, but why not mix it up? Also, I do appreciate that most hunters -- 90% -- can't shoot accurately out at the ranges where the trajectory of the .30-06 may fall behind the faster cartridges. I know I don't have any business shooting game at 400 yards. I've shot a pronghorn at 240 yards, and that felt like a long shot.