This is a good thing for smart criminals
Next time I commit a robbery, I'll leave my phone at home. When the police get a court order to look at my phone records, and find out I was "at home" during the time in question like I said I was, my lawyer will have to be made aware of this court order when my case reaches trial. And he'll make sure that the jury knows that the police checked my phone records, and would have claimed evidence that put me at the scene of the crime had it revealed such, but instead found evidence corroborating my story. He'd be sure to introduce evidence of other trials where phone location records helped convict others, making it sound almost as good as DNA evidence to a gullible jury.
So long as I'm smart enough to not leave fingerprints or be caught with the stolen goods in my possession, which would both be difficult to explain away, in the case where a prosecutor has a weak hand this might be enough to tip the scales and set me free. All this does is provide another tool to catch stupid criminals, and law enforcement hardly needs another way to do that when stupid criminals have not only brought their phone on a robbery but even posted selfies of themselves WHILE COMMITTING THE ROBBERY!
Oh wait, I forgot I'm living in a country where the Constitution no longer matters, and they are going to access this data without a court order. So I'll never be able to know that they looked and found nothing and used it in my defense. Corrupt cops of which there are many will be able to look up phone records for people they are harassing, ex girlfriends or potential girlfriends they are stalking, and so forth. Another tool to continue our march towards a police state. Never mind!