While The Diary could be placed safely under the prog umbrella, its specific style is harder to pinpoint. Its theatrical atmosphere and use of classical instrumentation suggest a folk rock approach, especially on the more upbeat tracks such as "Heart of Amsterdam," but it varies in mood throughout and lacks aggression even on its heaviest segments. It is bombastic and conceptual as all of Arjen's projects tend to be but its Old World aesthetics capture the feel of the 17th century star-crossed lovers narrative in a way that his sci-fi oriented themes could never match.
Whichever side you prefer, the album is put together and performed quite well. The clean production allows the various instruments to stand out and the vocals are always performed in an exotic but always relatable fashion. The songs also offer a lot of moods as previously mentioned; the opening "Endless Sea" and "Shores of India" have a dramatic air, "Heart of Amsterdam" and "Eyes of Michiel" offer upbeat waltzes, "The Moment" goes into a more somber direction, and even the largely atmospheric "Epilogue" ends with a whimper that avoids feeling like filler.
It's hard to tell which of Arjen Lucassen's projects are meant to be further developed and which are destined to be one-offs (I'm still waiting for another Guilt Machine album, damn it). I get a feeling that The Diary will be an example of the latter but its unique aesthetics may make a followup unneeded. The presentation is classy and the style could be enjoyed by fans of several different genres. My only hope is that they have period appropriate costumes and sets when performing this material live.
"Heart of Amsterdam"
"Shores of India"
"Eyes of Michiel"