Developers depend highly on sites like LEiMobile to do app reviews. If an application costs money, developers have to provide the press with review codes or gift the app to them as writers do not want to pay for something they can get fro FREE. Previously Apple has limited iOS developers to just 50 review codes per app update. Once those 50 were used up, they could not generate anymore until they released a new version of their app.
Now iOS developers have the ability to generate 100 promo codes that gives them more possible reviews. Even if they do not use all of them for reviews, they can use them for promotional purposes like contests and giveaways. This is great news and I know lots of developers have been waiting for this!