I think the vectors that you have clearly put more time into look great, but the more simple vectors that would of taken less time aren't appealing to me, as they lack sufficient detail. I'm by no means an artist but some of the stuff you have on there are so simple (eg. the Nature vectors), and would hardly take any time to create myself for free, so why would I purchase them. You need to try to keep the same level of detail with all your vectors. I feel you got a bit lazy with some of them and just added a gradient to finish it off. Your Background vectors are great, your Weapons are cool.
Your best work are those that have a bit of depth to it and a slight 3D element.
As for the site, the whole site could do with a tidy to be honest; the Asset Store could be displaced much nicer. Compare your Asset Store to your Amazon Store.
