It is that good. Ok, negative first, just one, and even it is neglible. The Dreamcast is not well-supported by the world at large. Japan seems to hate the machine for some unexplained reason and Americans, though better, don't much like it either. The reason this is a negative is that it affects game development.
Low sales means low support.
Luckily, this hasn't been a problem. The DC has a library of over 150 games out now or by the end of the year. Thats in just 15 months, awesome. I have as many DC games as I do N64. The Dreamcast has proven quantity doesn't much matter when almost every title is a must-buy.