A beloved nostalgia act like Outrun is always hard to follow, and Sega didn't do themselves any favors here by waffling about whether this was actually a "sequel" or not. They sold it as an upgrade/conversion kit for existing Outrun cabinets rather than a stand-alone game, and while it ran on the same hardware it's really a fundamentally different game from the ground up.
The theme is still racing between checkpoints in your sweet Ferrari, but with a lot of tweaks to the gameplay. It's an all-new course, taking you across the United States from New York to Los Angeles. The legs of the game are divided between checkpoints you have to reach in time as in the first game, but now you can insert another quarter and start from where you left off rather than being booted back to the beginning. That's probably because the game overall is longer than the first, and you also can't choose branching paths as you could in the original.
There's also a few new twists to the driving action. Hitting the other cars no longer wipes you out, simply slows you down a bit. A police car will also show up and chase you once in a while. There are also three "major checkpoints" along the way where you'll get your choice of a car upgrade. And you can also fire off a periodic "turbo boost" to quickly ramp up your acceleration and temporarily max your top speed. The biggest addition, however, is that you now have a rival driver. Gary Oak has apparently decided to challenge you and will constantly be hovering around you the whole race. You don't have to actually beat him at any point, but if you come into a major checkpoint behind him, the mercenary hussy riding shotgun will bail on your car for his!
It's the same solid gameplay of the original with a new course and some neat new graphical effects (borrowed from other Super Scaler games), so I struggled for a bit to understand why I just didn't find this one as appealing. Part of it is the play control; this was designed to be played in the arcade with a steering wheel, and unless you have a port that is rebuilt to be optimized for gamepads/joysticks or for a specific home wheel, you just don't have the necessary responsiveness to handle tight corners and will be stuck playing at something of a subpar level. The handling here feels even worse on gamepad emulation than the original game, though you can still brute-force your way through the tough parts with the new instant continue feature.
I think it's more that the additions all feel tacked-on and pointless. The cop car is the biggest offender; it rarely shows up, is only on-screen for a few seconds and I've never seen it accomplish anything at all. Turbo also feels like it's not really doing anything when all the other cars on the screen just kinda hang with you when you use it (and without the arcade-precise wheel it's also totally useless anywhere but the rare long straightaway).
The rival driver *could* have been a good addition, as having Gary Oak swipe yo girl at each checkpoint gives the player some impetus to do better than the bare minimum to get past it. Unfortunately, they use one of the worst, most heavy-handed rubberbanding scripts I've ever seen. He's simply constantly around you no matter what you do. Use turbo on a straightaway, a second later he's casually sauntering up your ass. Wipe out, he's waiting patiently a couple seconds ahead for you to catch up. It really reinforces the idea that your driving skill doesn't mean anything at all when there's never any real distance between you.
It turns out that variety of the branching paths in the original actually meant a lot to the game's success, too. Having a shorter game with varied paths (but having to start over upon failure) made for a more compelling experience than a longer "turismo" across the country with no stakes and the ability to plug another quarter to continue at any time.
It's based on the solid bedrock of the original Outrun so it's not a bad game ... just disappointing that it feels like half a step backwards.