Super Paper Mario is a great game that I don't regret buying or playing at all. However, it could be a lot more.
Controls - 9 The controls are simple, easy to learn, and fairly responsive. Menus are easy to use, and it is easy to switch between characters, pixls, and select items. The quick-menu accessed by pressing 1+2 is certainly good, because reaching your thumb back to press + can be hassle. The only bad part of the controls is the motion sensing, particularly Style Moves can be a pain to pull off, having to vigorously shake the controller after jumping on an enemy.
Variety - 8 The biggest variety in the game is definately in enemies. The game features over 150 enemies (including dark versions of some). Gameplay is relatively varied, but for the most part it sticks to traditional Mario platforming style. There are a few arcade games, but nothing worth going into a lot of detail about. The game also features not one, but two Pits of 100 Trials, where you go through 100 rooms of enemies consecutively. The biggest issue is the monotony at some parts of the game (one in particular, if you play you'll know what it is.) There is also the issue of having to flip to 3D and back pretty much constantly, so you don't miss a hidden door or pipe or item, while at the same time having your 3D meter be limited. Replay - 6 The game is worth playing again, even after you've beaten it. After you are done, there is still much to do (discussed below in "Depth".) It would also be worth playing through the entire game again as well. I don't know what else there is to add, really. I can say it's good enough to play again, but I don't honestly know how long it will be until I take it out of the case again. The arcade games aren't really good enough to warrant playing a lot, and there is no multiplayer element.
Sound - 7 Sound effects are probably the best section of the sound in SPM. Enemies make appropriate sounds, as do pixls. Bowser has a nice roar, Peach makes....noises. However, as the main character, I felt that Mario could have been a bit more vocal. He is essentially a mute, and only makes occasional "yea!" or "nono!" comments, and the rest is simply gestures and fervent head-nodding. The music was mediocre and nothing special. While some of the tracks get stuck in your head, it's nothing you want to learn to play on the keyboard like most other Mario titles. Since the game is based off of traditional artwork and gameplay, I would have liked to see Koji Kondo encorporate old songs into the game, or at least base the songs off of the same range of notes and tempos.
Depth - 10 This game has a lot of depth if you are an obsessive-compulsive "collector" type of person who likes to complete games 100%. The game features a lot of recipes, which you can use to turn ordinary items into dishes and try to get them all (along with the cooking disks that have new recipes on them). However, I didn't cook more than a single recipe that is part of the storyline in the entire game, and I don't see a point in doing so now that I've beaten it. Along with recipes, there are also cards of all the enemies and characters in the game that you can try to collect, and they appear sort of like a Pokédex under "Cards" on the menu. The same issues as with recipes apply. You can also get Treasure Maps, which will lead you to a location where you can get an item, but usually nothing too special. But I suppose if you are into collecting stuff, this game has a lot of depth beyond the main storyline.
Overall - 7.9 Super Paper Mario is a great game that I don't regret buying or playing at all However, it isn't going to be a classic in my opinion, and it definately isn't best-in-series.