One of the best kart racing games around and a huge step forward for the franchise.
Visuals: 9.5/10
Something SEGA always does well are the visuals, the game looks beautiful and it's awesome seeing so many memorable SEGA games/characters in full HD. The animations for the cars look great and reminiscent of Transformers and the tracks themselves are a sight to behold. Each character has a unique car and several of them have cool animations when transforming. The game holds up at a very smooth framerate, although I have encountered a couple of glitches but it rarely happens.
Sound: 10/10
Hearing those classic SEGA tracks remixed gave me shivers the first time I heard them. Each racing track is accompanied by a soundtrack that almost always perfectly matches the atmosphere of the stage. Hearing voices for characters like Vyse is pretty sweet also.
Gameplay: 9.5/10
Before, most kart racers would always be compared to MarioKart, as Nintendo not only created the genre, but has upheld a high standard for the genre ever since and Sonic & All Stars Racing Transformed meets those standards and surpasses some of them greatly. For one, this is not your typical kart racer that everyone can easily pick up and enjoy, this game is very challenging to master and goes at a much faster pace than MarioKart. Of the 3, the airplane is easily the hardest to master but if you can master handling the plane, it'll easily put you at an advantage over many others. The boat is the hardest to handle as you can easily be steered off course and have a hard time recovering, but it also presents the most opportunities to do stunts to gain boosts.
Stunts in the game work similarly to MarioKart and work exactly the same way they did in the Sega All Stars Racing. Basically you do a stunt in order to gain a boost, but unlike MarioKart where you do a stunt and you automatically get a speed boost, All Stars Racing requires you to land that stunt in order for you to gain a boost, if you land before finishing a stunt, you get slowed down. The more stunts you're able to execute before landing, the better your boost. With drifting, the longer you drift, the better your boost, if you can get it to level 3, it'll basically be the same as using a boost item. Unlike the previous entry and MarioKart, you can actually carry over your drift boost to another turn provided you press the drift button almost immediately after switching directions. While stunts in cars and boats give you boosts, stunts in the airplane only give you boosts if you use it to avoid an obstacle (called risk boost), "rolling/flipping" in the airplane is easily the most important element to master as it can allow you to make sharper turns, build up your drift boost and allow you to maneuver through the course with ease, which is why the airplane is the hardest vehicle to master as flipping/rolling pretty much has to become second nature to you while racing. The items are also pretty balanced and require a skill to use, it's not like MarioKart where you can just let a red shell go and it'll easily hit the person in front of you, and if you are a skilled player, you can dodge most items. However, due to the balanced nature of the items, if you can gain a good lead on the rest of the racers, it'll be nearly impossible for them to catch up as there aren't any items meant to specifically slow down first place (except one called Swarm but it's something you can avoid unless it catches you in a narrow path).
A great addition to the game is the World Tour, something I HIGHLY recommend you doing before taking on the Grand Prix option as the World Tour will easily hone your driving skills with a set of races and challenges that will teach you how to effectively race and use items. It's also where you unlock all the characters. Every time you use a character, they gain experience and level up, with each level they gain a new mod for their car, changing some of its stats. The main difference with most of the characters is their All Star ability, say you like Tails's All Star ability (one of the best) but you prefer to use a car with a great top speed and boost ability, use Tails enough and you'll be able to select a mod that improves his top speed and boost but at the expense of his acceleration and/or handling. Having this does encourage you to use all the characters instead of the previous game where each character only had on given set of stats.
The game can get rather frustrating at times, for example, in some challenge races, the computers will drive much faster than you naturally, which makes these races unfair since the moment they pass you, it's hard for you to catch up, especially since most offensive items don't do a good job of slowing down an opponent who's far ahead. Also some of the tracks have some rather irritating design choices, like the Burning Rangers track which puts a few flat walls or hooks close to narrow paths which can stop you dead in your tracks and require you to turn 90 degrees in order to get back on track, which obviously can make you drop several places.
The variety of characters is pretty nice although I wouldn't have minded sacrificing say Knuckles, Shadow (even though I like using him), Amy, MeeMee and Reala (their presence seems unnecessary since they look very similar to AiAi and Nights) in order to have characters like Ryo (Shenmue), Opa Opa (Fantasy Zone), Billy Hatcher, the ChuChu's and a Virtua Fighter character to add more variety to show off SEGA's rich history. Although characters like Danica Patrick and Wreck it Ralph are pretty interesting additions.
The offline experience alone is still enough to justify the $39.99 price tag, especially since multiplayer allows up to 5 players, however, there is online multiplayer and while it's still a bit hard to find random matches, from what I've played so far, the online works extremely well and I didn't encounter any lag or slow downs during my races.
Value: 10/10
With the huge World Tour mode, Grand Prix, offline and online mutiplayer, Sonic & All Stars Racing Transformed offers a great deal of options that can take up lots of your time. The World Tour alone will take you many hours to beat, especially if you're aiming to earn every single star (because many of those challenges can be torture to beat).
Overall 9.5/10
Sonic & All Stars Racing Transformed is a great step forward not only for the series, but also for the genre, Sumo Digital made a statement that Nintendo should make the next MarioKart is a crossover game instead of pulling characters only from the Mario franchise, which I very much agree with. Don't look at MarioKart 7 and think that this game is a shameless rip off of that, if anything, it provides the best elements of Diddy Kong Racing and MarioKart 7 and turns it into one hell of a racer. While it maintains all the chaos and craziness standard to a kart racing game, it also provides a great challenge that will take even the most seasoned gamers a while to master. For me, this game is the new standard for kart racers and I hope Nintendo and the others take notice of this game and use it to take the kart racing genre further.