To my ears, they did everything on that album better with their previous efforts, but I guess since you don't like those albums that much, it makes a weird kind of sense that you'd enjoy Fall Of Hearts, rather than being disappointed by it as a rehashing of material you already enjoy.
In general these guys have been one of my favorite groups for over 20 years, and I can listen to something by them at nearly any time, depending on my mood. I don't know that I have one "favorite", but I have memories entangled with most of their stuff. A chronological journey follows.
1998 - I got turned on to them when Discouraged Ones was released: living by myself, listening to a bunch of Swans, going out to the local goth clubs, trying to write songs and make art in my spare time. Something about the dismal yet warm simplicity of this album sucked me in. Top picks: "I Break", "Nerve"
1999 - I fell in love with them because of Tonight's Decision: better musicianship, more involved songwriting, vastly improved vocals, tighter sound, beautiful melodies. Swano behind the kit. I was still living by myself in North Carolina, prepping for college in NYC, feeling change in the air. This album hit me right between the eyes. Top picks: "I Am Nothing", "No Good Can Come Of This"
2000 - I got hugely into their older albums: early days and late nights in New York City, Brave Murder Day the soundtrack to passing by a church on 14th st, or walking through leaves in Washington Square Park. Wrapped in aloneness, the sparse nature of the music was a perfect fit. In retrospect, this might have been the happiest time of my life. Dance Of December Souls slots in here too, although it took a while before I'd fully appreciate it. Top picks: "Brave", "Murder", "Rainroom"
2001 - I was transported to heights of rapture by Last Fair Deal Gone Down: Napster days in the freshman dorm, sharing their existing albums with my girlfriend, watching songs from this album trickle in hour by hour, chatting online with the people who were uploading them, snorting those shit quality mp3s like an addict. We bought the CD as soon as we could find it. Daniel Liljekvist was a wizard behind the kit; they took yet another leap in musicianship and songwriting, and found that perfect, organic, mid-heavy sound. It seemed like they had finally succeeded at what they'd been trying to do all along. Top picks: "Chrome", "The Future Of Speech"
2003 - I was initially very disappointed by Viva Emptiness, but eventually came around: this album was the beginning of the mechanically polished mixes that would become their mainstay, with their insistent downbeat replaced by an awkward bounce. Jonas brought his unfortunate penchant for gratuitous curse words to the forefront, like a six-year-old who calls someone a "dildo" without knowing exactly what it means. This album was argued over by me and good friends in apartments with cheap gas stoves and overactive radiators. After listening to it for long enough, the stuff I didn't like faded into the background. I'll put this on whenever. Top pick: "Evidence"
2006 - I was blown away by The Great Cold Distance: having worked my way into an appreciation of the previous album, this one didn't throw me for a loop. Sharing a godawful, decaying house on truck stop property in central PA with a friend, the early release of "My Twin" seemed to encapsulate the post-apocalyptic emotional landscape I found myself in, and spoke to me of finding small joys at rock bottom. Months later, the full-length was everything the singles had promised - another evolution in their melodic sense, some newly stark rhythmic bones behind their songs, and that awkward bounce harnessed to purpose as a lulling sense of groove. Mattias Norrmann's bass lines made a lot of good things better. Top picks: "My Twin", "Soil's Song", "July"
2009 - I got disappointed again by the stilted and artificial quality of Night Is The New Day: I still don't love this album, and I only put it on when I'm on a road trip, or if I'm in a Katatonia mood and I've already played the rest of them. Good sections and fond memories of it as part of a Thanksgiving celebration at my old apartment in Brooklyn do little to outweigh the forced heaviness and clunky songwriting. Top pick: "The Longest Year" (which has some of the best and worst qualities of the album as a whole)
2012 - I found a pleasant surprise in the comparatively relaxed and un-forced Dead End Kings: after NITND, I wasn't expecting much, but this album sounded like the logical successor to Great Cold Distance. It felt like a presentation of the same ideas from the previous couple of albums, but brought into new focus - streamlined, good dynamics, no momentum wasted on non-sequiturs and half-baked riffs. Katatonia was back! This album became a frequent companion on road trips, so for me it's the sound of moving through a shifting landscape, watching ribbons of asphalt spool away beneath me. Top pick: "The One You Are Looking For Is Not Here"
Fall Of Hearts sounds like a mishmash of leftovers to me; by far my least favorite of their albums and the only one I don't own.
I think the tracks they save for their EPs are mostly awesome; I never minded that they weren't on the albums. They're cool little nuggets of greatness scattered here and there like rewards for digging through the catalog, and I think by and large they stand well on their own, while some album tracks are better in context. An extra few songs would have made any of the albums feel bloated. Sounds Of Decay and Teargas are probably my favorite Katatonia EPs; "Sulfur" has been one of my favorite songs of theirs since I first heard it.
Live, Katatonia has been all over the place. They were awful the first two times I saw them - thin sound, hoarse vocals, no stage presence - but well after I'd come to accept them as a studio band with no live chops, I saw them touring with Opeth, and they were phenomenal. Jonas has very little charisma; he's at his best when you can tell he's forgotten that anybody's watching. Dan Liljekvist was their beating heart onstage, professional and flawless. If I had fuck-you money, I'd probably pay some of it to see them reunite with him at a good venue.
I'm going to also give props to early October Tide, Diabolical Masquerade, and even some Bloodbath. Nystrom and Renkse are a great team and they've been behind a lot of my favorite music. I don't get into what their bands have done over the past couple of years, but that's a blip in proportion to what I do like, and I'm still interested to hear what they do next. Viva Gloominess.