I'm [i]really[/i] glad we have more vault space. But there are a few usability issues with the two pages that I would like to see addressed.
1) If there are enough weapons to require two pages, the weapons that are regularly swapped between characters always wind up on the second page. And of course, when you open the vault, the first page is always displayed first. Suggested fix: Put weapons (and presumably armor) added to the vault at the top of the list, not the bottom.
2) After looking at the Details of an item on the second page, closing the details returns to the first page. This is a hassle because it's necessary to return to the second page if you're looking at multiple items. (See # 1 above for a common scenario.) Suggested fix: When closing the details of an item, always return to the page that the details were opened from.
3) The yellow border is no longer displayed for items that are fully upgraded (leading to more detail views). I can see where the new infusion feature means that there is room for more weapon improvement, so the weapon is no longer "max leveled" currently. However, now we can no longer tell at a glance if all the perks have been completed for a weapon. Suggested fix: Add an indicator for completed perks. Possibilities include a different colored bar overlaying the green "experience" bar as perks are purchased or an icon that's added or removed when all the perks are completed.