Storyline: 4/5 
 Characters: 4/5 
 Writing Style: 2/5 
 World: 4/5 
 I was genuinely surprised to find that I liked this (and much more than the first four). In my estimation, though the series till now has undoubtedly been significant, it has not been good. Perhaps that is a sacrilege amongst science fiction fans, but after building up psychohistory (Part I of V of the first book), it has all gone downhill. Asimov manages several feats here that he had previously been less successful with: 
 1) Broad worldbuilding - Trantor was nicely developed in the beginning as was the Second Foundation, but in those earlier books the development does not extend throughout the novel or further out into the galaxy. It was if all of Asimov's creative energies were spent on one segment, and he had nothing left for the rest of the book. Here, in Foundation and Earth, we get a much more extensive and developed view of the larger galaxy (albeit without the single, developed emphasis of the earlier books). 
 2) Social commentary - Whereas the earlier books traced the rise and fall of empires and was more devoted to historical trends, this one gave us much more on the trade-off between communitarianism and individualism. I did dislike how Asimov settled Trevize's choice between Galaxia and Empire (the choice made in the previous book), but there were some good ideas and arguments in the middle. 
 3) Characters - In a lot of ways the characters were unlikable. They were, however, understandable. The bickering between Trevize and Bliss became tiresome, but I could envision the two of them constantly harping at one another and annoying everyone else who happened to be in earshot. They looked for any and every opportunity to nitpick the other's argument, and generally they weren't interested in finding the truth as much as they were in defending their own predispositions. All this made for flawed but ultimately realistic characters. (view spoiler)[ In particular, I like to contrast this with the main characters' view of civilization. Deteriorating ecosystems and dangerous flora and fauna are unimaginable for Pelorat and company. I think this was Asimov's forecast of how "civilized" humans and culture would become as technology progressed. As civilized as Foundationers (and Gaians) are, however, they can still be prejudiced, narrow minded, petulant, jerks. I'm not sure that Asimov intended this contrast, but it adds a jewel to the Asimov future: however technologically advanced we become, we're still immensely parochial. (hide spoiler)] 
 4) Tie-ins - There is a satisfaction in seeing disparate elements brought together. The current fad in movies with prequels is a good example: we love to see how pieces of the story from different timelines and vantage points connect. This is the novel in which Asimov brings things together from the Robot series, Galactic Empire, and Foundation. It may have not been masterfully woven, but it was a pleasure to read. 
 For all the merits of the book, there are certainly still demerits worth mentioning. 1) Asimov's dialogue is still horrible, and far too much of the novel was spent in conversation with two characters. 2) One of the worst contributions the Foundation series made to science fiction (and space operas especially) is the pacing. That push to make the progression fast and exciting can dumb down the novel. Several times the characters reacted both idiotically (and out of character) so that Asimov could end the scene, move on to a new location, or to create some mini-drama. 3) One chapter was particularly unfortunate as the tie-ins were overhanded and dampened the enigmatic aura that had accompanied Trevize's quest. By the end of the novel, it seemed like Asimov had stopped caring about what happened before and was breaking ground for a sequel instead. The most serious damage done was against (view spoiler)[ psychohistory. I've waited since the first book to see the mechanics of this more fully worked out, and not only did Asimov not do so, but he carelessly (and in the span of a single paragraph) ruined it completely. I can see why the ending ruined not only this book but the series for die-hard fans. For myself, I didn't care for the originals very much, so when the ending butchered psychohistory, the Second Foundation, and Gaia, I wasn't as traumatized. (hide spoiler)] 
 Were it not for its status as one of the greats, I think I would have given up on the series after the last book. I'm glad I didn't.