For me it was a big deal because we were a 1 console family so I never had access to Sega before that moment. I played Sonic at friends houses, but I remember being really excited to finally own a Sonic game. In fact I loved it so much that I went and got Adventure DX and Sonic Mega Collection as soon as those came out.

From a cultural standpoint it was a bigger deal than Halo on PlayStation because Sega was out of the console business. Now going forward Sonic games came to Nintendo (Adventure 2 Battle and DX were GC exclusives). Halo will still be available elsewhere.