I purchased two GE Water Heaters from Home Depot (my house needs two because of a remodel). They have a 12 year warranty from Rheem, but only the first year is Full Service. The remaining years are parts-only.
Last Sunday morning I woke up to cold water from one of the heaters. I tried a relight, but it didn't stay lit. I called GE's tech support line and the young lady talked me through checking the piezoelectric starter (which was fine) then a full relight sequence. This time it appeared to start running normally. I waited a couple of hours then tried to shower - the water was cold and when I checked the unit it had gone out again. I called GE back, but they close early on Sunday.
Monday morning I called GE again. They told me I had to check the "environmental conditions" next - that is, have a plumber come out and check the venting, check the air circulation, and check the gas pressure. The venting I can see - it was as it had been. The air circulation hadn't changed and wasn't blocked, and I told her so. She told me that I would have to have a plumber check the gas pressure and get the number, and he would have to open it up to check the internal venting before they would do anything more.
They are worthless. It's basically a case of - if it breaks, call a plumber. If a part has failed, you MIGHT get the part shipped to you, but don't count on it.
Their 12 year warranty is essentially a 1 year warranty. Don't be fooled. Aside from a unit that starts leaking badly, I can't imagine a case where it would be worth the paper it's printed on.
The answer may be to buy an extended warranty from Home Depot or whomever your dealer it - and factor that into the cost of the unit. Clearly GE could care less.