If you grew up with this game, this is a good conversion (though a controller is a must) and the HD graphics mode offers a nice, if subtle upgrade to the original graphics. However, like most of Sega's early 3D games (Virtua Fighter excluded), it was somewhat lacking in polish to begin with and as such hasn't stood the test of time well. I have a lot more respect for the team that did Journey of Dreams after revisiting this than I did before because, while that game failed spectacularly, the original NiGHTS didn't exactly give them a lot to work with. A lot of the reason why Journey of Dreams was bad is that NiGHTS itself, by modern standards, isn't very good.
I'm giving this a recommend, but that only applies if you're already familiar with the game and would like to play it again without dealing with old hardware. On that level, this succeeds abundantly, and I hope Sega will continue to do re-releases of their older games. But if you're not already a fan of NiGHTS, this is a skip. It's a product of a bygone era of gaming, and a company that was struggling to find its identity in a changing industry, and it shows. NiGHTS was clever and beautiful for its time, but now it mostly seems counterintuitive and dated.