Well, first, don’t waste your time pointing to a low quality items and wondering why they got approved. Current quality requirements are extremely low (at least for ThemeForest, I can’t speak for graphicriver etc.) and reviews are inconsistent. It is how it is and you can’t do anything about it so just don’t waste your energy on that. If you want to compare your item to something already on the market, try to pick the best of the best and try to get close to their quality levels. Also ask yourself the most important question: why would anybody buy your item (if it got approved) if there are gazillion of 404 pages already. I’ve said it countless of times on this forums, but getting your item on the market is the easy step. The hard step is to make actual sales. And that’s now even harder than ever because the market is extremely oversaturated.
Now, that’s it with the philosophy lesson and here is some actual criticism:
The align of “cant find this page” is completely off. Why it is aligned to the right??? With all due respect, but this thing alone tells me that your skills are very lacking.
Padding of search input and align of its magnifier icon. Again, way off. If you don’t see that bottom padding is bigger that the top or you don’t have a problem with that, then I am sorry but you have much to learn.
The rest of it is mediocre at best. Just bunch of images, titles and text with poor typography.
The only interesting thing are those background lines shaping the 404 title. But that’s really not enough. Especially when you have such very basic issues mentioned above.
You may think that all those are just minor things, but such minor things make a difference between a professional design and an amateurish one. Especially in the PSD when you have every single pixel 100% under your control. You need to be pixel perfect, you need to be very critical to your work and you need to come with something if not original, then at least very, very polished. It is not a rocked science, you just need to put enough time into that and you will get there. Check out the dribbble.com (and countless of other sources) for some inspiration. Don’t try to reinvent the wheel with the basics (typography, white space, etc.), there are many, many articles on the web about that stuff. Then just add a bit of your own flavour and make it unique. But it is important to be aware of the fact that it will take time until you will be any good. Good luck.