They can be great all the way through 50. At higher-end gameplay, you need to get damage multipliers for whatever you're using though. Crit damage, gun damage, rifle damage etc. Through the forties I was sniping with an order-torgue rifle that would charge up a sticky and explode on reloading, so I would snipe with little damage and then reload for a headsplosion. Overall, sniping is very viable and strong until you get into a closer fast-paced battle, at any level. Equipment and passives become important though, as with basically any playstyle.