Hehe I just happen to be listening to thier new album right now

Well I don't particularly think they are on a steady decline, SoDWoL is definitely not as good as its predicessor The Dreadful Hours, but that album is one of their best albums ever, so obviously they are not at the end of the line. My main gripe with the new album is although it sounds very good and is a good listen it lacks the excellent songwriting of some of its predicessors. Still a solid release, just shamed by some of their others...
Breift Summary:
As the Flower Withers- Doom/Death which definitely has it's moments, but when the band leans towards the death side it becomes rather weak.
Turn Loose the Swans- Dark and dynamic with an excellent mix of clean and growled vocals, lots of violins and keyboards and excellent songwriting. Very passionate and emotional.
Angel and the Dark River- An emphisis on their gothic elements and a elemination of the death elements. Nevertheless a brillant work with phenominal songwriting, melodies, and violin gallore. Their best work IMO.
Like Gods of the Sun- Even cleaner then Angel... this album really lacks heart (other then a few standout tracks such as "A Kiss to Remeber" and "For My Fallen Angel") and the songwriting is rather dull and unoriginal
34.7888% Complete- Hated by many as the band abandons doom metal all together. The loss of their excellent violinist and drummer altered their sound a lot. This is dark, somewhat electronic metal. Hard to describe. Good but far from great.
The Light at the End of the World- A return to doom metal, including the return of growled vocals. At times excellent, but way too much filler.
The Dreadful Hours- The bands passionate and powerful ressurection with excellent song writing, tons of dynamics and a wide array of vocals.
So I'd say pick up Swans, Angel and Hours, as all are excellent. If you really like those then go for the others...