I like the song Prime, Petteri use his "beat box" style of playing this song where the acoustic guitar is used more of a drum. This gets that beat going throughout the song. This type of percussive style is also used by the Japanese guitarist Kotaro Oshio.
♫ Kotaro Oshio - Brand New Wings - HD Video - Hand to Hand Album - Japan ♫
If I were to criticize this song, it would have to be the middle part around 2:00 min in to the song that I don't really like. That's just me, I would have gone another "direction" in the song. Still overall this is a very nice song, and the technique that Petteri use is certainly unique. There are not to many guitar players out there today that do this type of style.
When it comes to tuning, this song is played in DADGAD tuning also called D modal tuning or Celtic tuning. And actually this same tuning is used in Pettei's song Distorted Love. Both songs share the "beat box" style and are both very well done.
♫ Petteri Sariola - Distorted Love - HD Video - PHASES Album - Percussive Beat Box ♫