Encore is an excellent rifle. Since it has interchangable barrells, suitability really depends upon the caliber. I have a relative who is retired from the US Wildlife service in Alaska. He has hunted Alaska and all over the US with an Encore, plus he's been to Africa 3 times with it, and is coordinating for a safari in 2008.
The only MINOR drawback with any is single shot firearm, is that it takes a few seconds longer to put the second round down range. Plus, you have to remove the gun from your shoulder to eject and replace rounds, which means you have to re-acquire the target (as opposed to a bolt action that can eject and insert a fresh cartridge without being removed from the shoulder). You can still get second shots, if necessary, but trying to shoot a wounded animal while it's hysterically running away, no matter what is in your arsenal, is an excercise in futility anyway. This being so, any single shot rifle like an Encore, H&R, Rossi, or muzzle loader, tends to teach you to be very deliberate on that first shot count, and not rely on subsequent shots to finish the job.
All that said, the Encore is an outstanding product, perfectly acceptable for plains game, plus may even help become a better marksman and hunter.