First, to explain the unusual byline: Heinlein left several pages of detailed notes for a novel that he never got around to writing. In the Afterword, Spider relates that at a panel at Torcon, the existence of these notes were mentioned in a Heinlein panel which Spider was on. Someone in the audience shouted that Spider should write it. And to make a long story short, he did. It's a little unclear just how much of the plot actually came from Heinlein, but the writing is Spider -- but with a plot that's a little more under control than sometimes.
The writing is quite engaging, and the characters we're supposed to like are likable. There are characters we're not supposed to like, that I thought were being treated unfairly until the ending when they reveal that the hero's judgment of them was correct. There's some interesting world building and some engaging detail. But there are some big annoyances. First and foremost, the main story hangs on something horrible beyond imagining, and using this event as an off-stage plot device just to whack the characters into some plot twists just seems wrong. Second, the way things fall out from the horrible thing smells fairly strongly of deus ex machina -- things worked out just too conveniently. The emotional roller coaster the plot drags the hero (and hopefully the reader) through involves such extremes of acceleration that he could easily be expected to be reduced to jelly. And the key science is really not believable as science; we're treated to entirely too much "we just can't explain this magic so you'd understand it". It's not hard science fiction; I wouldn't be so uncharitable as to say it's not science fiction at all, but some would.
Still, I did enjoy it. It manages to end up as hopeful as it possibly could after the magnitude of the horrible, and reasonably satisfying. But there's enough to dislike that I'm sure a lot of people will hate it, enough that I'm a little uncomfortable recommending it. If you're a Spider fan, you'll be fine with it; if you're an old school Heinlein fan, you may have more trouble. I think I'll give it an 8 out of 10.
**** PLOT SUMMARY -- MASSIVE SPOILERS ****
Joel Johnston is a promising musician and composer who's just graduated from college and hopes to go to on to study at a first-class music school. And he's found the love of his life, Jinny. But on their prom night, after he proposes marriage, Jinny drops a huge bombshell on Joel. She's lied about her identity; she's not the ordinary girl she claimed to be. She's actually the granddaughter and heir of the richest, most powerful man in the whole Solar System, one Richard Conrad. Jinny and Conrad assume that since Joel has passed Jinny's test, he will happily shelve his own life and be trained to take over the Conrad empire. Joel tells them both to get stuffed, escapes the Conrad's secret hideout with the help of Jinny's 6 year old cousin Evelyn (who tells Joel before he leaves that she will marry him someday), and signs onto a colony starship that's just leaving for an obscure star in Bootes. This is a sub-light expedition, but one which will get very close to C under a magical drive called a Quantum Ramjet, which only operates while being babysat by a very special person called a Relativist. There must be a Relativist minding the drive every second, and it can only be done by someone whose meditative focus is at a level only achieved by a few hundred people in the whole human population. (The Relativists in the story, in addition to being masters of meditation, seem to be on quite a high ethical plane as well, but Spider never explicitly makes any pun about Moral Relativists. Perhaps it's meant to be inferred.) A Relativist can only do this trick for 6 hours at a time, and only for 6 hours out of every 24. And if the drive stops for more than a few minutes, it can't be restarted at all. When two of the ship's six Relativists are killed doing their thing, the expedition is looking very shaky. One other point of background is that while the ship is limited to lightspeed, it does have some Heinlein telepaths aboard. Telepathy is instantaneous. And the ship's telepaths suffer near-simultaneous mental almost-meltdowns when Sol explodes. Due to extremely convenient timing and some inconsistency in the nature of the explosion, they manage to get the word out to the ship. (The explosion is described as the entire mass of the Sun being instantly converted to energy. I'm fairly certain that in the face of the release of this much energy, it wouldn't make any difference if you were behind a planet or not; all matter in the Solar System would be instant plasma. But the telepaths on the ship get to experience the deaths of their twins.) We never actually resolve for sure whether the Sun blew up in a coincidence involving previously unsuspected physical phenomenon, or if it was enemy action, but the latter is implied. There's one fairly nice speech, before the drive dies, about how the remains of humanity should deal with that. But there's also a lot of soapboxing about 9/11 (Spider manages to blame Nehemiah Scudder, in Heinlein's canonical future history, on the 9/11 attacks, grafted unmodified into Heinlein's universe, and also to explain how terrible it is to have all of humanity wiped out in terms of 9/11, *retch*). Now, suddenly, the ship and the colonies already established are all there is of humanity. And the colonies are going to be sterilized when the wavefront hits them. The strain of this drives the least stable of the four remaining Relativists to suicide. The remaining three manage to keep the drive going for a week, but they lose it. Just as everyone on the ship is trying to decide if they want to suicide themselves or just wait for the radiation to overtake them, Joel is summoned to the Bridge, where he discovers Conrad, Jinny, and Evelyn. It seems that Jinny seduced a physics genius, a Tesla-esque character named Andrew who responded to the challenge of being chosen as a mate by the heir of the Conrad empire by inventing a faster than light drive. This drive is even more complete bolonium than the quantum ramjet, but it has the interesting property that it doesn't care how much mass it's being asked to move. It was conveniently on its shakedown cruise (with Condrad, his key aides, Jinny, Evelyn, and the inventor aboard) when the sun explodes, and it was conveniently in Earth's shadow at the time. But when Andrew mentions how the drive doesn't care about mass to Joel, Joel realizes that Conrad is just using the people aboard. Evelyn demanded that they rescue Joel because she wants to marry him, and Conrad wants to stock up on provisions so he doesn't show up at the first colony he plans to take over with his Conradness in a weak bargaining position because he's out of food. When Joel verbalizes that the talk of the schedule that will be required to ferry the passengers a few at a time to their destination is bullshit, Conrad's chief aide, "Smithers", pulls a gun on Joel and tells him to shut up and cooperate. But Conrad's social secretary, Ms. Robb (for some reason, Spider thought that "lay Ms. Robb" (for Les Miserables) was the pun of the century, or at least the novel), pulls out her own gun and blows Smithers' head off. The good guys manage to take out Conrad's bodyguard, and all involved tell Conrad to shut up; he's not god anymore. Joel and Evelyn (who thanks to time dilation has caught up with Joel enough in age) fall in love and live happily ever after, the end.