It is said that Friends of the Dark were promised power and immortality, but near the end when the Dark One touched the world, everything withered and died (even food went foul). And he had just barely touched it. I imagine when he won there wouldn't be anything fun or desirable in the world. So what exactly was promised to attract Darkfriends? I sure wouldn't like being immortal in a world of desert and dead trees..
The DarkFriends were never promised anything.
The Darkfriend Creed: “The Great Lord of the Dark is my Master,
and most heartily do I serve him to the last shred of my very soul.
Lo, my Master is death’s Master.
Asking nothing do I serve against the Day of his coming,
yet do I serve in the sure and certain hope of life everlasting.
Surely the faithful shall be exalted in the land,
exalted above the unbelievers; exalted above thrones,
yet do I serve humbly against the Day of his Return.
Swift come the Day of Return.
Swift come the Great Lord of the Dark to guide us and rule the world forever and ever.
The goal of Darkfriends was to work their way up, to be recogonized by the dark one himself, and in so being recognized they would wish to join the ranks of the Chosen, who WERE promised immortality and places of power after the Dark One was freed.
Spoilers for the last few chapters of the Last Battle.
However, in Rand's battle with the Dark One he discusses and realizes that the Dark Ones plan is total destruction of the world, so the Dark One has been lying to the Chosen the whole time.
Reincarnation or eternal life is really more of a tease than a promise; as the Creed makes clear. Additionally, nearly every darkfriend believes a more mundane quantum of power or wealth will manifest in their day-to-day lives. Darkfriends often achieve some level of success, but its unclear whether their allegiance to the shadow is of any benefit. It is certainly the case that the shadow is more interested in recruiting skilled, ambitious or otherwise useful agents than providing any on-the-job training, as it were. Most often, the books portray a darkfriend having to make some sacrifice in pursuit of their duties to the Great Lord. There are several darkfriends who regret joining the shadow, often stating that they just joined for the rewards without thinking the cost would be so great.
Building on Himarm's answer, it is revealed that the Dark One does possess power over death. So despite being the Father of Lies, he's not lying about that, exactly. During the course of the books (spoilers for every Forsaken to follow):
Several of his Chosen are killed throughout the book, and brought back to life in different, fully adult bodies, with their memories, personalities and powers completely intact.
Ishamael is killed by Rand in the Heart of the Stone and reincarnated as Moridin (roughly translated as death) and named Nae'blis, the second in command below the Dark One and ruling the rest of the Chosen.
Furthermore, by the end of the books, it is revealed that Ishamael only wants to die permanently, without being reincarnated. Whether through the overuse of the True Power or through knowledge shared with the Nae'blis only, Ishamael knows that the Dark One wants to destroy the world and break the Wheel of Time completely. Ishamael believes this will result in his permanent death, which is why he serves the Dark One so fervently.
Ishamael probably gets his wish, as Rand kills him again during the fight at the Bore and he is cremated.
Balthamel is killed by Rand at the Eye of the World and reincarnated as Aran'gar in a woman's body, going by the alias Halima.
Aginor is killed by overchannelling the One Power at the Eye of the World and reincarnated as Osan'gar at the same time as Balthamel.
Greandal is killed by Shaidar Haran, the hand of the Dark One, and reincarnated as a hideous hag.
Lanfear is killed by Moiraine or the Aelfinn or Eelfinn on the other side of the portal they tussle into on the docks of Cairhien. The Dark One reincarnates her as Cyndane ("Last Chance").
The final score is
5 deaths with reincarnation (above), Rhavin, Be'lal, Semirhage killed by balefire and out of the Dark One's reach, Sammael killed by Mashadar and unable to be resurrected, Moghedien captured by a sul'dam with an a'dam, Mesaana incapacitated in her cover Aes Sedai body, Asmodean killed by Graendel and not resurrected for unknown reasons, Demandred killed by a sword at the last battle, shortly before the Dark One's prison is reforged and presumably unable to be resurrected.
Oh, and Mazrim Taim is named Chosen and killed by Egwene at the last battle. It's unclear whether her counterweave for baelfire leaves him ressurectable or not, but presumably sealing the Dark One in a new prison breaks his ability to capture and resurrect newly dead souls. I did say every Chosen would get a spoiler!
Most darkfriends speak of their eventual reward as eternal life, not just reincarnation. It is never made clear if the Dark One can preserve life or if he is limited to capturing souls when they die from ordinary (non-balefire) means. The Forsaken are preserved while sealed in his prison, but that may be a function of the prison, or the time contraction that occurs simply by being near the bore. Aginor and Balthamel were sealed closest to the bore and aged considerably, appearing disfigured and ancient when finally released. Balthamel even resorted to wearing a mask to hide his face, which is alluded to lack most of its skin.
It is not mentioned whether or not reincarnation was used during the War of Power. It is not revealed how widespread certain knowledge of this power becomes before the end of the book, but nearly every darkfriend who lives long enough to speak of it is shown to believe it for truth. Several of the Black Ajah are highly covetous of the power over death that would come from their reaching the rank of Chosen. It is unclear whether being Black Ajah had any more perks or promises than a typical, powerless darkfriend. The Dark One is never shown to resurrect any non-Chosen servant. Finally, it is also not clear what limits on the Dark One's power were enforced by his original prison, the imperfect patch placed after the War of Power by the Hundred Companions, or at the end of the book series – he may have only possessed or cared to exercise reincarnation power while the seals on his prison were weakened to the point of breaking.
At least Asmodean had an interesting reason to turn to the dark. From the Fires of Heaven:
Asmodean claimed it had been the thought of immortality, of endless Ages of music, that seduced him; he claimed to have been a noted composer of music, ...
Not your usual control-issues or desire to see the whole world burn kind of nonsense!