They're fine as musicians though their operatic melodic metal sounds pedestrian to me, I played their last album to my 14 year old son and he said: This sounds like the metal version of a Disney musical.
Manowar are embarrassing in a way that they shoot their mouths off and then back down. Back in the eighties there was some conflict between them and Twisted Sister and Dee Snider asked DeMaio for a fight. Which Manowar refused to do. Which is ok if they had said: "Grown men don't fight about this." But they weren't brave enough for that. Instead they had Ross the Boss (their former guitarist) write letters to his former Dictators bandmate Marco Mendoza (TS bassist, not the Whitesnake/Ted Nugent sidekick with the same name) that please, please would Snider stop goading them as they could not afford to back down "before their fans" or apologize for whatever grievance Snider felt. Grown men can apologize too. You can even do it in a loincloth.
Manowar are hypocrites. They mouth off about how Kiss and Judas Priest only use a tiny portion of their backline (the rest just for show) and then Joey plays a "bass" solo on a Ric clone that uses guitar strings (tuned down), has an action "on the other side of the neck" and only half the width of a regular bass fretboard. And Flight of the Bumblebee isn't even accurately (or nicely) played. He's been doing it for more than 20 years now, someone teach him a new trick or tell him to do it on a real bass. Real men play real basses, Joey. Not downtuned guitars that are souped up via amplification.
Manowar aren't Iron Maiden, they lack that prog aspect to their music. And they aren't Judas Priest because they pretend to believe what they're doing where Judas Priest play their music with a twinkle in their eye (and some elegance).
That said: I like their presumptuous over the top version of Puccini's Nessun Dorma on their penultimate album.
Death to false metal, yeah right.
Uwe
PS: What I credit them for is that they are not Ted Nugent who at a recent gig in California cracked jokes about how Rodney King should feel "lucky" the cops didn't shoot him; with largely black bouncers standing by to protect his sorry little white ass.