Of course, there are some obvious differences between the Dreamcast and PlayStation version, and it all starts in the visuals. Cleaner visuals, less pixelization during zoom sequences, and an overall improvement in texture quality (especially on dinosaurs) are the most apparent graphic enhancements. Special effects look cleaner, but have not been retouched or redrawn. The game seems to run at the same frame rate as its PlayStation version, but I didn't expect that to change for the better. For the most part, Capcom didn't give it the "translation of justice" treatment that we've seen on other Dreamcast titles (i.e. arcade to Dreamcast Soul Calibur), but there's no doubt that Dreamcast owners will have a better looking version.
So is that it for Dreamcast changes? Almost... Dreamcast owners will be able to access the secret mini-game, "Operation: Wipeout", at the beginning of the game, and play dress up with Regina's extra costumes. The Dreamcast D-pad setup isn't clunky or hard to handle; a few minutes to adjust to the controls are all you need. And in certain sequences, I believe the loading duration is a bit less than the PlayStation; bear in mind, I played the game on the PlayStation nearly a year ago, so I'm basing this off my memory, that has been often labeled as "selective".
And yes, that's it for the changes. The gameplay is exactly that of the PlayStation version, and for the benefit of non-gamers everywhere, here's the paragraph that diagrams what type of game Dino Crisis is (Gamers should drop down to the next paragraph). Part of a select secret team, you take control of Regina, a hot redhead with the skills of a Navy SEAL. You're dropped on an island where some strange things have been happening around the private research facility. Soon, you discover these "strange things" are full-fledge, man-eating dinosaurs ravaging the island everywhere. Dino Crisis is essentially a clone of Resident Evil with a few added gameplay mechanics (weapon loss and Danger events), and some new eye-candy (real-time backgrounds and yes, I know RE: Code Veronica has them as well... I'm generalizing). There's no doubt that it's fun, but if you're going to compare it to Resident Evil: Code Veronica, Dino Crisis is hardly a competitor.
One strong reason for most people to get Dino Crisis is its cost. Priced under 20 bucks, it's definitely worth a purchase if you're a fan of the survival/horror genre that Capcom has mastered. It's just too bad there's really nothing the Dreamcast version of Dino Crisis has to offer to those of us that played it last year. I can whole-heartedly recommend this game to Dreamcast fans who have never played the game... just don't expect any huge bragging rights over those PlayStation owners.