(Haven't updated nor do I care to. But it's par for the course of Sony to patch the exploits as soon as possible. If wololo goes "YEAH NO" then expect a "stability update" soon after to close all those holes. You aren't getting PSN access if you want to keep the exploit)
For those wondering where the themes are, they're coming tomorrow. From the blog:
Starting tomorrow, non-game Themes including Crystal, Four Seasons, and Stitching will be available to purchase and download from PlayStation Store on PS Vita. Themes from fan-favorite PlayStation Vita games, like Uncharted: Golden Abyss, Tearaway, and Freedom Wars are all coming soon. Youll be able to manage downloaded themes through the PS Vita systems Settings app.