Google has tried to convince potential buyers for laptops and desktops running its Chrome OS that they need a powerful processor for its web-centric approach to computing. Nonetheless, after being saddled with weak specs, Chrome devices are starting to pump up the hardware a bit.
Alas, the Core i5-2450M is a second-generation Core processor (a.k.a. Sandy Bridge) and not a third-generation model (a.k.a. Ivy Bridge), which means you are stuck with HD 3000 integrated graphics instead of Ivy Bridge's more-robust HD 4000 graphics. Nonentheless, a Core i5 is a far more powerful CPU than the Celeron B840.
The new Chromebox is otherwise the same spec-wise as its predecessor: 4GB of RAM and 16GB of solid state storage. It's also about $80 more expensive than what the previous Series 3 Chromebox had been selling for, though it seems to be currently out of stock from retailers like Amazon and Newegg. That makes it still about $200 less than the cheapest Apple Mac Mini, though that nettop comes with an Ivy Bridge processor and 500GB hard drive.