Yeah, this is Nintendo trying to fix something that isn't broke. I personally enjoyed it for the time I spent playing, but I'm in limbo currently(haven't played in months). The sticker concept was cool, but the randomness of what stickers you need to defeat bosses is just kind of of broke. I would like to see them make another one and flesh out the ideas a little better.
I would say it's to Paper Mario, what Starfox command is to the snes/n64 games. Some cool new ideas, but I would have just preferred a more straightforward game that follows the meat and potatoes of what the series is all about. But in Nintendo's defense, people would have complained in that situation to, saying "this is the same old game, with no new innovations".
Nintendo used to be masters at adding enough "new", but still keeping games familiar and appealing to long time fans of the series, but lately they seem to be getting lazy IMO.
I really hope Luigi's Mansion 2 doesn't suffer this same fate. The original was awesome, and the only thing I personally would like to see is a refinement of the games mechanics and more of what was in the first. I know it's going from a console, to a handheld, so this is always going to be a fine line to walk, and I believe this is why Paper Mario was so different. They tried to make a game that appealed to fans, as well as make it playable in a quick sit down handheld fashion.
I would rate it a solid "B" for where I'm at in the game, so that rating could go up or down after I finish it, and for 30 I think it's a good buy. Just go in with an opened mind and you should be fine.