If you have taken the pains to check if your idea is worth it, then it probably is or it will be soon.
What I mean by that is that you seem to be in the habit of researching before leaping and properly baking an idea. This alone increases changes of your idea being great.
The common definition of ‘Great Idea’ in an application context would be an application having enough potential that its users like it so much that they are happily willing you to have their money to let them use it. You’d want enough number of such users to make a profit from this project. That’s a successful application.
If that’s the case, a large part of an app’s success depends on, as with any product, on marketing. Lots of good apps are lost due to lack of good and timely marketing strategy. But that’s for another time.
That said, those lots of users your marketing generated, wouldn’t have much use of the app if it wasn’t useful to them. Marketing only makes sure your great idea is a success.
Enterprises applications are different. You want the application to alleviate a particular problem or improve your current process. Is the problem pain enough or the improvement good enough to warrant development costs, training and adapting time? How much do you save? Answer your own question.
So What is a Great Idea?
If you have though an idea that no one else yet has but is so obvious you wonder why you didn’t get that ages ago? or something that makes doing a task lot easier? That’s a great idea – duh. Just be sure to have enough users to make it profitable.
Most application ideas these days are ensembles. They do greatly reduce their users time and effort by bundling up services in to a single platform. Time savers seem to be big winners in both business and consumer markets. Or an improvement on an existing service. This one’s a bit tricky. Success comes to depend largely on how effective you are at convincing users to migrate from your competitor and how quickly can the other guy copy the improvement.
Packaging the idea is something you should think about hard. This can some times lead to discovering new uses for the idea and a market segments. This can lead your idea from being an improvement to being a different service entirely. A big game changer.