His run is no doubt impressive and will definitely be remembered. Whether it'll be remembered fondly in retrospect, only time will tell. I really dug his run at first, but found I lost interest after Sinestro Corps, when the rest of the Rainbow Lanterns started appearing. Some were introduced well (Orange, Red), but most were really shoddy or too quick. Plus, I've never been a big fan of the Rainbow Lanterns in general. Blackest Night made it just plain ridiculous, with Black and White (even if it was inevitable).
Also, I really hated when Blackest Night went from another good GL story to a super-mega-money-grabbing-blockbuster DC crossover. Long-term is going to really hurt them because the trades are a mess. If someone heard about Blackest Night and picked up just the main trade, assuming they'd get the whole story, they'd be lost as hell. Hal disappears a few issues in and then magically returns towards the end with a whole bunch of new characters that haven't been mentioned or introduced previously. Oh, you'd have to read the Green Lantern issues to get that story, which is ridiculous from a book market perspective.