Is oven an important factor in getting great baking results?
For reliable baking you need to know what your oven is doing. If the internal temperature fluctuates wildly, you're dead in the water: replace it. If it's fairly stable, spend some time learning it. Get a decent oven thermometer; set the oven's temperature control to, say, 350 degrees (F) and let it settle; check what the oven thermometer says. Then work through various other temperatures, so that you know what you need to set the oven's temperature control to in order to get the internal temperature that you want. For example, to cook something at 350 with my oven I set the control to 325; to cook at 450 I set it to 420.