Radical? I don't think it's more radical then Prime.
I don't know about not being able to find weapon/suit upgrades (are we 100% sure there won't be any at all?) but there will be the usual energy tanks and missile upgrades to find. According to Wired's hands-on there was a couple of upgrades to find in the demo and you had to blow up walls to find those.
I am interested to learn more about Samus, so there's no gamebreaker there but I don't want MGS cutscenes.
The way you replenish missiles and health is new and I'm a bit sceptical for now. I don't know if it will make the game easier, or if the game will be harder. I can imagine having low life when surrounded by enemies to be a real pain.