In my experience, proper execution is second to marketing and distribution. You can have the best product out there, but if no-one knows it exists you'll have a

In my experience, proper execution is second to marketing and distribution. You can have the best product out there, but if no-one knows it exists you'll have a hard time selling anything. If you're looking to enter the same market as another product you know there is a market for it. So the problem isn't whether the idea is fundamentally good or bad -- it's whether you'll be doing something special enough to attract attention in a market where other people have already been working for quite some time to dominate distribution channels and get visibility.