The Windows Phone app store is full of apps, but also full of possibilities ~ Matt Lacey: Creating Better Apps

Over on the DVLUP blog they've just announced that they've given away design and UX consultations to 30 apps in the store.

While that's all well and good this phrase caught my eye:

"popular apps with many positive reviews and good ratings are not necessarily doing well because of a great UX or design, but because they are functionally really good and are addressing real user scenarios!"

For the apps which will benefit from the consultations this is obviously a good thing but it highlights an opportunity for other developers.

What this says (or rather reminds me) is that competition isn't a bad thing. Just because there's already a successful app in the store that does the same thing as you want to build an app to do, it doesn't mean you shouldn't. If you can provide a better user experience.
A brief look through the store shows a lot of apps which display very little effort has been spent on creating a high quality user experience. Many of these apps are successful because they were functional and in the store first. They may get updated with a better UX. If not, that a great opportunity to compete against them. If you can do the same thing functionally but provide a better experience, the fact that you weren't first won't be an issue for long.