It's a little frustrating. Seems like there's a lot to love, but the most common complaint is the combat. I don't know why Nintendo feels like they have to reinvent the wheel each time when they have a perfectly good system collecting dust.
I thought it was because they wanted to avoid the risk of cannibalizing sales between the Mario & Luigi and Paper Mario series since both were starting to make appearances on the same platforms. I wouldn't be surprised if Nintendo went back to making Paper Mario a traditional JRPG if the Mario & Luigi series is truly dead following AlphaDream's demise.