I must say I am impressed with the new class & subclass takes. They feel interesting and even a little elegant. As for the Ranger Poultice, it sounds like an excellent feature that really captures the utility and flavor of the Ranger. I don't see it as being exclusive to the Ranger, others probably know how to do similar things, but it is exclusive to the Ranger among adventuring classes. There are probably herbalists and healers throughout the world that have similar lore or abilities, but they are not adventurers, and the sick and injured brought to them usually have the benefit of a long rest, which ameliorates the need for such 'band-aids' as the Ranger's ability only deals with Hit Points and they are rather abstract. Sure the Druid may know a thing or two about using herbs and plants to treat injuries, but he does not need the practical application of such as he has spells to do it and while the Barbarian is usually out in nature, that does not mean he has the lore and skill to do what the Ranger does, he is focused on other things. Sure his tribal shaman/wise-man/witch doctor may have the same or similar ability, but that is not something he focused on.
This also underlies why they probably went with the spell-casting Ranger as a base in the first place: it allows them to give out nice, flavorful abilities in pre-packaged chunks that are relatively balanced and contained; without having to give excessive rules and tables or (to some) unsatisfactory hand-wavy explanations of why this mundane-ish ability only works once every so long, or always works no matter the environment, etc. 4e kind of burned them there I guess. I think if they would have done this in the PH, they probably would have added more Ranger like maneuvers to represent some of the utility magic taken away from them, but this is a good start. It does kind of undermine the Ranger in a small way as to why they are a separate class and not a subclass of Fighter, but it is tolerable.
I think the Sorcerer is a real start to making the class better. It is at the same time more generic and more flavorful, largely because the choice of domain spells gives the player much more leeway in building their PC. It may require more Hit Points in addition to more armor and weapons to really make a utility, mix it up gish type, but time will tell.