Your only main advantage is that you can probably move faster through iterations than the established provider. But also, you've got to do some catching up and then making sure you navigate through the deadly sea of feature-hell. Use the product, understand it, go through forums and talk to users, figure out their pain points. If you find an opportunity, just one niche thing you can help them with, then go all-in on that. It will help get some users interested. They'll say things like, "if you also had X,Z and Y, then we'd be able to switch completely" — and that's where you'll likely crash your boat again when conquering the hell that is the sea of possible features once more. It's doable, but it's a lot harder than it may seem at first.
