So if you live in a glorious PAL region this game has already been out for several weeks, but if not, Mario & Luigi Dream Team will be released in the US on August 11. This games plays much like its predecessors, with Mario and Luigi taking part in turn-based combat, with an onus on reading enemy tells so you can avoid getting hit yourself.
This time around the 2D sections take place in the Dream World, where the duo combine their power and fight as one (I'm not making this up) to take on large hordes of enemies and sometimes Luigi turns into a tree. This game also maintains the excellent soundtrack the series is known far and can actually be funny sometimes when it's not slamming on the brakes to start another tutorial. If you have a 3DS you should buy this game, Tom Nook will still be waiting for you when you get back.