I'm another recent Sabaton discoveree, thanks to LooseCannon/Perun on chat the other month. I can't say that the later albums are worse but they've certainly been played less by me.
Back when I was first getting into music (and a little again these days because I am not listening to as much new stuff) I used to usually only have 1-2 new albums at a time, and I would put them on in the background whilst doing other things. If I found something catching - be it tune, lyrics, whatever - after a few rotations I would sit down and give it a real listen paying full attention. Let's just say it's been a long time since I have found myself 'joining in' before the first play has ended (Panzer Batallion!).... whether that's good or bad I don't know. It could mean over simplicity/predictable, but I like the songs so who cares!
Voice reminds me of Lordi a bit, but less growl.