Yup it's Mario and Luigi: Inside Bowser Story.
Despite receiving universal acclaim (Metacritic: 92) and lots of good press, this game's thread has been struggling to stay on the front page and currently only rests at about 7 pages. Considering the quality of the game I'm finding it peculiar and I wonder why GAF is collectively sleeping on the title. Even the usual JRPG fans that post in these sort of threads are absent. Perhaps they played it in Japanese?
Another idea is that maybe GAF got burned by the love it or hate it Super Paper Mario, which was enthusiastically hyped (32 pages) but which many considered to be not actually all that good.
Is it the Mario subject matter? Sure it's lighthearted, but it still has some of the best dialogue that I've seen so far this gen. Is it "hardcore enough?" I'd say it is. Even though it has the veneer of a kiddie RPG, it's actually secretly pretty challenging as well. You're not going to find yourself grinding of course, but like all Mario and Luigi games, if you stop paying attention and miss a few defending moves, you'll quickly find yourself in a dire situation.
Looking at metacritic scores for other JRPGs this gen it seems to me that this is actually probably the best released so far. The average scores for Star Ocean, Blue Dragon, Lost Odyssey and Eternal Sonata for example are far below that of Mario and Luigi 3.
There have been lots of great RPGs this gen but many have been of the SRPG or western styled hardcore dungeon crawler variety, which I know many average gaffers would stay away from. Mario and Luigi 3 is by far the closest to the classic, accessible 16 bit JRPG that we've seen yet this gen.
Perhaps the answer really is that the JRPG is dead or dying?
Come on get your act together GAF!