For me, this is the defining album of the early Genesis years, although perhaps an acquired taste, it has grown on me over the years and has never lost its magic.
From the first moment of Peter Gabriel's stand-alone voice singing "Can you tell me where my country lies? ... " there is a stamp of something bold and different in what is to come in the following songs. The rest of the opening track contains some moments of pure genius and a flowing energy that takes you right into the album.
It is the atmosphere that runs through the whole 50 minutes or so, evoking images of medieval England with an almost mythological air in both the lyrics and the instruments.
Another quality to this album is its diversity, from a classical opening to Fifth of Firth on the piano by Tony Banks to the catchy "In your wardrobe" track, which if I recall correctly from a documentary I saw, was the first taste of single success that Genesis had, getting into the top 20.
Overall, although this may not be to everybody's taste, it is a must for any Genesis fan, and worth a listen for anyone else! If it catches your imagination, then it will last you for years of relistening.