It's a big change, but it might be the right one. Thinking of the top of my head, some concerns are...

You might not get the same breadth and variety of entries this way. I've always felt that community applications have always been very 'System and Utilities' category oriented, but I don't feel there is the same amount of games or other applications coming through. By removing the categories you'd be removing an incentive for developers to work on these types of applications, imo.

I also think that by having categories you can help stretch the skill set in the community by encouraging and rewarding developers in areas they normally wouldn't enter unless there's a shiny new device to be won If it's going to be one big pot of entries all judged together then I, as a developer, am going to stick to my comfort zone in order to make the best quality app i can rather than push the envelope or try something new. For example, I see Cocos2d-x is the featured Qt project of the week (Nokia Developer Team twitter feed). It would be awesome if somebody was to use it to create new games for the competition and bring those skills into the community.

Another concern is presenting the entries for judging. Picking a random number in my head.. 50.. if there are 50 entries in the competition, are people really going to comb through 50 application descriptions to compare and judge them? Having categories breaks it up into 5 or 6 apps which are similar that can be more easily compared. Also, if I am only interested in media or location based applications I know where to go to find them, I don't need to search through a long list to see if there are any.

Hmm.. that's all the possible concerns I can think of at the moment. What does everyone else think?