Its had some mixed reviews alright.
Im a big lover of Vintersorg as a solo/project artist, as well as his work with Borknagar.
I also love Oystein's style, and their combination works well on Terra. I think ultimately Terra is one "for the fans"... unofrtunately, its not different enough to stand on its own merit without taking Borknagar into consideration.
Its a good album, dont get me wrong, it has a very icy feel to it which is great. I think their NEXT release will be a good one. Terra is about Andreas & Oystein cutting their teeth together imo.
On a side note, Andreas' drum programming on this album, as with Waterclime, is fucking FANTASTIC. He's getting VERY VERY good at it.