It takes time (work) to turn the eggs, but I have not minded turning by hand. It forces me to check on the eggs, temperature, and humidity, allowing me to make adjustmants as needed.
If you are planning to hatch large numbers of eggs, you might want to invest in one, but if it's just for a few here and there, I wouldn't bother (unless you are never home to turn them manually).
I'm currently incubating my 2nd batch of eggs, so I am by no means an expert, but I did have a 100% hatch rate with shipped eggs while turning by hand. The eggs in the 'bator are looking really good, too (also manually truned).
I considered purchasing a turner but decided I didn't really need it because I am home all day and can turn the eggs as needed. Your situation is probably very different, so you may want to invest in one.
Best wishes with your hatch!