What other portable racing game can compare? None.
With that being said, I can definitely say Burnout Legends is a kick-ass racing game on the go. I've played a variety of portable racing games throughout the years including ones on game-watches. The element missing from those games is one of the primary abilities on Burnout Legends: the ability to smash the crap out of the other contenders in style and be rewarded. Every time you successfully ram the hell out of another racer, you're treated to a slo-mo of the wreckage like some action chase scene out of a Hollywood movie. The more chaos you cause and the more maniacally you drive, the more boost power is given to you which will allow you to pull ahead of the pack real fast.
Even when other racers take their revenge on you and send you flying hundreds of feet into the air, you're able to use your flying wreckage as a weapon during slo-mo by maneuvering yourself in the way of other cars causing those poor suckers to crash. When done right, the chaos and destruction can be so damn beautiful that they should be an olympic event.
If you're into alternative rock and metal, you'll love the soundtrack. The songs' speed, thrashing guitars, and insane rhythms fit the races well. If you're not into the songs, you can simply pick and choose the tracks you want off and on in the options menu.
The game also offers police pursuits in which you operate a cop car and have a certain amount of time to chase and stop a getaway car by smashing it relentlessly until it's out of commission.
If you just want to see how many cars you can lay to waste with your car, there's a series of games for that too.
The only thing I wish was available is free roam. You can't cut through the alleyways or jump the railing and tear through the beach and emerge on the other side. There are alternate paths, but they're limited which is okay since you'll be wanting to keep your opponents in close proximity to you anyway just so you can send and see their asses flying off the cliff.
There are some people who won't like this game. If you're not into smashing up other cars, rock music soundtracks, and the lack of plumbers with mustaches, then this game ain't for you.
Otherwise, hell yeah, pick this game up.