Game Revolution: Review

Review of the game giving it a B+.
http://www.game-revolution.com/games/dreamcast/adventure/ecco.htm

GameSpot: Ecco - Defender of the Future: DC Review

GameSpot's thorough Review of Ecco the Dolphin: Defender of the Future, Dreamcast Version. Contains all kinds of media such as Screenshots and Movies, as well as Codes and FAQs.
http://www.gamespot.com/dreamcast/adventure/eccothedolphindotf/

GameSpot: Ecco - Defender of the Future: PS2 Review

GameSpot's thorough Review of Ecco the Dolphin: Defender of the Future, PlayStation 2 Version. Contains all kinds of media such as Screenshots and Movies, as well as Codes and FAQs.
http://www.gamespot.com/ps2/adventure/eccothedolphindotf/

PlanetDreamcast: Games - Reviews - Ecco the Dolphin: Defender of the Future

Planet Dreamcasts review of Ecco, Defender of the Future. They gave it a pretty good rating.
http://www.planetdreamcast.com/games/reviews/ecco/