What I don't get about the store is this --
1) They don't have enough recommended items by default, you need an item changer to list six items per slot. With 5 rows and 6 items per column you have 30 items per champ...99% of games you're going to be buying the same 15-20 items, so pack that first page full of all appropriate items (ie, everything that's not Rabadon's Deathcap on Riven) and 99% of the player base won't need to hunt around in "All Items"...ever. You still have your variation in builds; their AP mid is beasting so I go Hexdrinker, their AD carry is strong so I'll go for an earlier Randuins, etc.
I strongly recommend anyone who dislikes the store goes and finds an item changer, and puts the 30 items they're most likely to buy on their main champs in the "Recommended" area...on Lee Sin I never even leave that first page.
2) They decided to use half of the width of the store with the new "filter" system. I think the filter system makes sense, it's nice to click on "armor" and "AP" and find an item you want when their Rengar is fed but you still want to build some damage. However, the layout just doesn't work.
Something like this
on the other hand let's you see a MASSIVE selection of items, cover a lot of ground with the scroll bar, and still enjoy the new "filter" system. In case my two minutes of photoshop weren't in depth enough, the top there with classes like "DEFENSE", "ATTACK", etc can be further broken down. Those individual boxes can be selected and the resulting items will be filtered. Click "DEFENSE", all defense items are shown. Click "ARMOR", all items with an armor component are shown. Combine "ARMOR" and "ABILITY POWER", and you find the Zhonya's quickly.
However, when just scrolling, you cover roughly twice as much ground with the horizontal item layout as opposed to the vertical layout...it just makes more sense.
For reference, here's the store as it appears now, in all it's ugly glory: http://i.imgur.com/tVzm8.jpg
tl;dr rearrange the store like this http://i.imgur.com/irKRu.jpg