Submit or Die. Often.

For fans of the original Sin and Punishment, I can without much hesitation say this: Yes, Star Successor is the sequel you wanted. It blends the the fast-paced action of an on-rails shooter with the twitch-reflex timing of the bullet hell shooter as well as its predecessor. The Wii remote makes a much better pointer than the Nintendo 64's analog stick, and the rest of the controls transfer flawlessly. So if you enjoyed the confined action of the first game, there's little in the way of deviations to that formula, so for better or worse, you're in familiar territory.
For the rest of us, Star Successor does manage to be fun for a while. Most players will be able to work their way through the eight stages on normal difficulty if they persevere long enough. Just like you remember or just like the people who remembered will tell you – depending on which crowd you hail from – Sin and Punishment is no joke about letting you know your limits. There'll be cheap bosses (stage 3's melee boss comes to mind), times when you don't think the ending actually exists, and the occasional “screw this,” moments. And you're right to have those moments. It'll be okay.
See, Treasure's really good at what they do. Here they've stretched the rail-shooter concept much farther than I thought they could. There's a certain cinematic quality and set-piece battle design that will constantly surprise you. There were several moments during my run where, after finally bashing my head against a boss and winning where I thought “God damn, that was hard. But it was actually kind of cool.” There's a surprising amount of creativity going on between all the “Game Over” screen you're likely to see. There's a reason why the original game reached its cult status.

But for most of the people not totally indoctrinated by the original's masochistic tendencies, there isn't much more to do after seeing the end once. Not that it's an ending worth seeing, mind you; the “narrative” consists of a bare-bones premise, ridiculous set-pieces, and at least one person with animal parts. Not to mention the game looks like it was made around 2003, which isn't normally something I'd condemn in a game like this, but Star Successor sure does seem to take pride in its awful story.
And if you're not a fan of gritting your teeth, you can tone down the difficulty or add a co-op partner, both of which will alleviate your pain, to the point where it just becomes monotonous and boring. And there's my biggest problem with Star Successor; it either assumes you're going to accept its challenge without question and finish the game no matter what, or it assumes that you're a complete idiot who needs constant health packs and the feeling of constant empowerment to enjoy anything. For developer Treasure, there is no middle ground.
If you're the kind of person who care about their high scores, they're here all right, but don't expect to top the online leaderboards unless you're willing to get through the roughly three-hour experience in one go; you die or leave the game, even after save, your score resets.
And if you don't care, then there really isn't much here for you after the credits. These games are made short to be replayable, sure, but I can't imagine newcomers are going to spend much time getting to know the nuances of the game if they beat the game on easy, or to the end more than once on normal or hard.
Star Successor's worth trying at least once, but not for its $50 asking price. There's absolutely some great things to see here, but only if you're willing to devote yourself to it, whether it be to beat the game or rack up high scores. I could've spent less money had I played it in the arcade environment that the game tries so hard to evoke. I think that's a pretty good way to keep things in perspective.