Im going to be the voice on the other end. The Dreamcast ties with the N64 for the worst normal game console system in my opinion (by normal, I mean from the NES til now. Of course its better than crap like pong and stuff like the Commodore 64). The library is full of mediocre games (RPG options are a joke) and the controllers are absolutely horrendous. I hear that it has bonuses like it can read CD-Rs and totally modifyable ... but you cant really polish a turd!
I think a lot of people will have the same opinion. That is why I would suggest researching very well (if possible playing one before the OP tries it). I believe the above is a very valid opinion.
If you like RPGs, the dreamcast is not your console (although it has shenmue which I consider the best). If you like adventure games, you can do better. If you like platformers the dreamcast is not your system. If you like racing games, you've got a few great options and a LOT of mediocre games. However, the dreamcast is HEAVILY loved by people who like the late 90s arcade genre. The dreamcast has a lot of ports from the naomi architecture from that time. If you like SEGA and Capcom arcade games, the DC is a good system. Both companies seemed to believe in and love the system.
For me, I also really like that it has some decent ports from the 32-bit era with playable graphics. I personally hate the PSOne, Saturn, and N64. The Saturn has a few gems, N64 has about 10-15 games I would actually play, and the PSOne only has the SQuare RPGs that interest me. In my view, the N64, SS, and PSone were way too underpowered for 3D. I remember thinking that at the time as well. The N64 did 3D decently enough (game design was horrible). The SS did 2D well, however this was becoming a 3D era. And the PSOne, in my opinion, did neither 2D or 3D very well. The DC was refreshing in that it did 2D very well and 3d at least competently enough. Also, during this time, I played most current games in the arcades. Thus, to experience games and nostalgia from the late 90s, the dreamcast is about the only option for me.
Ultimately, it comes down to personal taste and whether that jives with the system's personality. Try it out, if possible, before buying. Don't pay more that 35-40 for the system, and you should be able to resell with no problem or loss.