As someone who has played a LOT of adventure mode, I have to disagree with a great number of complaints about combat being voiced here.
Blunt weapons are quite effective against armored targets. True, steel hammers aren't as effective as those constructed from other denser materials, but I can't really think of a good reason to think steel blunt weapons should be more effective than ones made of copper or silver. I think the historical reason for the switch has more to do with the durability of steel, and since weapons cannot currently break, this does not matter. One definite problem with blunt weapons is that the combat AI is supremely dumb about using them, attempting to bludgeon fingers and whatnot, so they frequently seem less good than they are.
Bleeding to death happens all the time in the game. It is, in fact, among the only ways to kill some of the larger creatures, as severing their bodies does not work. Frequently creatures pass out from blood loss, and this makes them easy targets for other attacks, despite the blood loss being the real reason for death, so you don't get the message saying they "died from blood loss" come up nearly as much as you might expect it to.
I would agree that on the whole whips and scourges are too strong. Generally this is because a whip made of steel does not really make sense as a thing that could exist in the real world. I guess you can hit someone with chains, but I really wouldn't designate such an item as a "whip". In my mind the fix for this would be to simply remove them from the game, apart from possibly as disciplinary weapons (human equivalent of the hammerer?) and even then force them to be constructed from leather, since something with the flexibility to move as fast as a whip, and constructed from something as hard and heavy as metal would shatter your organs through armor.
As for the hitpoints thing, this is to be fixed at some future time by implementing "pulping". Currently you can mangle bodyparts to the point of unusability, but without explicitly severing the part, it does not actually come closer to being broken off or destroyed. I expect this will come up sooner rather than later, since all the necromancer/undead stuff is going to require a satisfying way to kill the damn things, so it is likely to be in the forefront of Toady's mind.