This game has quite a few flaws:
1. The platforming is let down because of the fetch quests, amount of chit-chat and exploration off the beaten path being a little futile (i.e no badges). It's also as easy as crap as most enemies can be defeated in 1 or 2 bowser flames, and falling off will only take away one heart. There is plenty of money in the game, so buying a crap tonne of health means you'll hardly ever get game over.
2. The RPG is let down because... it's not really an RPG. It's kinda a moot point, but the pedigree of Paper Mario 1/2 to be simplifed to some RPG "elements" in SPM was disappointing, to say the least. It's definilty a fun and original idea, but the RPG stuff is so tame, it might as well not be there.
3. The worlds, characters and places pale in comparison to Paper Mario 1/2. Of course I admit that the Francis the Nerd level was absolutly genius, and a few others warmed my heart, but remember the Murder Mystery on the Train in Paper Mario 2, or Tubba Blubba from PM1, or the spooky town in PM2 where everyone was turned into pigs, the Puni people, Hooktail's castle, Dry Dry Desert and it's eery ruins from the first. None of this in here!
The characters are also really lame. Their writing is mostly ok (some superb), but the design is downright lazy. Since when does Mario fight cubes, boxes, square and rectangles. I like Superstar Saga's mix of BeanBean people with the mario world because it was consistent and interesting, but SQUAREs are not interesting, and being mixed with Koopas, Goombas etc looks downright silly.
And then there are the helpers. Remember when you had a salty sea-dog of a bomb-omb, or a baby Yoshi that had a random colour scheme and you named it, or the Parakoopa with a messanger bag. I don't think a square with five circles around it really competes.
4. There are some bullshit sections that either suck or are just plain time increasing. Running in a
Whats up with that crap? Having to go back to the first part of the town to get a password, then entering a really long password? Running up and down a tower getting a book?
I didn't like the space shooter and water sections either, but each to their own. And while the tree tower provided some interesting puzzles, falling down was almost Wiimote-through-screen worthy.
They really dampen the fun I'm having with this game. For every interesting character there is an annoying ambigious and needlessly time consuming puzzles around the corner. For every funny Nintendo reference, its coming out the mouth of a character made in MS Paint.
It's an interesting title thats really original but the mix of genres hasn't locked like some would hope. For me, this is the starter before Paper Mario 3 and Mario Galaxy.