It was the last saving grace of Sega for the console industry, their swan song of sorts, but it also preserved the "theme" and "feel" of gaming in the mid 90's.
Dreamcast had games that had bright, vivid, and loud colors, whereas I felt that the PS2 was focused on realism, with gritty and pale colors. Most of the library for the DC has arcade game fundamentals in mind, some of those being a 60FPS frame rate and a unique gameplay experience; there's something for everybody in its library
Speaking of arcades, the DC was also the turning point for where home consoles were on-par with arcade hardware, though that's thanks to the DC being the little brother in a joint development project to its big sister, the NAOMI. The systems are nearly identical, just that the NAOMI has more memory to maintain fast load times. I grew up going to the arcades to get wowed by mindblowing graphical and gameplay experiences you couldn't get with a console, until the gap was bridged with the DC, so arcade conversions were 1-to-1, basically.