If you're buying a .25-06 for hunting, it's a great cartridge. If you're buying it for a long range target rifle, it isn't a very good choice. The .25-06 really lacks good bullets for long range shooting, but for hunting deer sized game it'll hammer them with authority.
When choosing a long range rifle you should always think about what bullets you'll want to shoot first. You'll want a good selection of high BC bullets, more choices means more possibilities plain and simple. After you find a few bullets to try you pick a cartridge with powder capacity to reach your desired velocity as well as a rifle with the correct rifling twist to stabilize the bullets. You will need to consider magazine length as well, so as not to limit your overall length of your chosen cartridge.
What the .25-06 has in spades is velocity, but is sorely lacking in high BC bullet choices. This means other slower cartridges will overtake and surpass the .25-06 at long range. That doesn't mean you can't shoot long range with the .25-06, just that you'll have more obstacles to overcome.
Like I said I love the .257 calibers for hunting and own a .25-06 and two .250 Savage rifles, with plans for a .257 Roberts if the right deal comes along. For deer and pronghorn the 117 grain Sierra GK bullet makes for dramatic DRT kills. I don't shoot sub 100 grain bullets anymore but they sure made for explosive kills on varmints. For sub 500 yard shooting of deer and vermin a guy would be hard pressed to find a more fun rifle to hunt with than the .25-06.
