This was one really good show. I want to make a comparison between the US, the Korean and the Japanese versions of this show.
The main difference between the korean and japanese versions is the pacing. The korean show encompasses around 5 seasons of the original version, whereas the japanese version focuses mainly on the first season, and some of the second/third season (for the last two episodes). Weirdly enough, it's more fast paced than the korean show. I think it's mainly because of the focus of the show. In the korean version, the focus is more on the wife and her love life; the criminal cases are almost second thought. Whereas the japanese version is more focused on the husband's trial. The wife is still the lead in the story, but it's all about how she deals with the trial (she has more of a proactive role in it than either the us or the korean versions).

Another big difference is on the character of the husband. The US and korean actors were oozing sex appeal, and pulled of being both charming and scary. Especially the korean version, where his personality is more suave and smarmy but also absolutely dangerous. The japanese husband has some charisma too, but he really can't compare to the previous versions. His actions are less grey than them though. The wife really sums it up well by saying "he's a great tactician but a clumsy person".

The third big difference is the part of romance. This is a japanese show, so I wasn't expecting much, thankfully. Yes there are feelings going around, but everything is very subtle. Many plot points that appear on both US and korean versions were changed here to much safer versions (a family picture instead of a pack of condoms for example LOL)

The fourth difference which makes the japanese show better than the korean, is pertaining to the cases. The korean show is competent, but the writing was a little lazy, since it was almost a perfect translation of the US version, which is fine except it leaves very little in terms of suspense. The japanese show is an adaptation in the true sense of the word, and the cases have been rewritten in a way that make them new and exciting. Also the denouement of the japanese show is better than even the us show.

The acting is top notch for all characters. The casting of the firm's investigator is excellent, she even has that "exotic" factor that added to the aura of mystery around her character. Unfortunately, the wife is not as stylish as in the other versions, but that didn't bother me because it was in line with her story too. All in all, this a very good show and I'll recommend it over the korean version for someone who already know the original show. If romance (and skinship) is a must for you though, I'll say the korean version is a safer bet.