There are four lessons one can glean from this case:
(1) Good police work is awesome to see. Check out pages 19 to 21. Wonderful work by Officer Scott Trudeau, then of the Livermore Police Department. Caught a killer, essentially on a "hunch" (as well as careful listening), long after the official investigation into the killing had gone nowhere.
(2) Bad stories can kill you. Literally. Check out pages 9 to 11. Defendant's story as to why he was not involved in the killing was absurd. Just made him look bad. Certainly didn't help him avoid the death penalty, and might have even contributed to it.
(3) Patently improper arguments can be made even in high-profile death penalty cases. Check out Justice Kennard's concurring opinion. Are you kidding me?! During the closing argument of the penalty phase of defendant's trial, the prosecutor had a large chart -- entitled "The Bible Sanctions Capital Punishment" -- and went on a long religious discourse (complete with quotations from the Bible) arguing that God wanted murderers sentenced to death. The impropriety of this extensive discussion is manifestly obvious to me. Sure, defendant's lawyer did not object, and responded by using this same line of argument to maintain that Buddhists didn't kill, that Jews only killed every 40 or 160 years, etc. But that hardly makes things okay. A jury's job is not to resolve religious conflicts about whether God wants the death penalty. Even if such a "resolution" by a human factfinder would somehow be possible. I agree with the Court that this doesn't require reversal here, since there was no objection. But it's a darn good ineffectiveness claim on habeas.
(4) Last lesson: Death penalty cases take a lot of the California Supreme Court's time. Check out page 160 (!) of the majority opinion. Not only for the fact that 159 pages precede it. But also for the Court's mention that the reporter's transcript contains over 3,900 pages, the clerk's transcript is over 15,000 pages, the opening brief is 745 pages (!) and the reply brief 522 pages, and even the Attorney General's brief is 375 pages. All for a killing that occurred over a quarter-century ago. In an appeal that is the first of many, many proceedings. State habeas, another state habeas, federal habeas, appeal to the Ninth Circuit, successive habeas, etc. Lots and lots (and lots) of resources.
Fortunately we've got money to burn.