How should a flight review be logged?
Short answer: log it however you like as long as you log it.

According to the FAA:


  When the applicant has successfully  completed the review, the CFI
  should endorse the pilot’s logbook to certify that the pilot has 
  satisfactorily accomplished the flight review.  The CFI should make
  the endorsement for a  satisfactory review in accordance with AC 61-
  65. The flight and ground time must also be  logged in the pilot’s logbook in  accordance with § 61.51(a)(1)


61.51(a)(1) simply says that "Training and aeronautical experience used to meet the requirements for a certificate, rating, or flight review of this part" must be logged.

So you do have to log both ground and flight time, but exactly how you do that is really up to you. The FAA doesn't require any specific logging format as long as the information is correct and CFIs, DPEs and others can see what they need to see.

Personally, I would note the ground time beside the CFI's endorsement and then log the flight time as I would for any other training flight. I've never met anyone who logged their 'ground instruction' time precisely (simulator time is a different story), but if you want to then you can do it any way that works for you. The FAA just wants you to log something that shows you did receive the necessary ground training.