Sega Dreamcast was the first ever 128 bit computer, and the last amount of "bits" that mattered (before computers went onto "Processor Speed"). What that meant was it could shift data twice as fast as the Nintendo 64, and four times as fast as the Playstation and Sega Saturn. Having powerful developers behind it such as AM2 and Sega meant that there were some unique games, arcade conversions that were spot on, and classic games brought into a new light.
The console also was the first to feature online play. It was slower than a tortoise with dementia, and not many games took advantage of it, but it was a step in the right direction.