I'm not a fan of remakes generally because typically the remake is a watered down and poor interpretation of the original work.
You specifically ask about the Conan remake. Conan: The Barbarian is NOT a great film, but it is freaking awesome to watch. The screenplay (credited to Oliver Stone although it was heavily rewritten) is epic telling a sprawling story but never losing the characters. And let's not forgot some of the famous lines. "Conan, what is best in life?" and "He is Conan, a Cimmerian. He won't cry, so I cry for him." John Milius is brilliant as director, especially the scene where Conan falls into the crypt and sees the Atlantean King and takes up a new sword. So much is done with one scene with only one line dialogue! And it's nearly a silent film. Conan barely speaks and neither do the other characters. The story is told through images and action and does not rely on heavy exposition.
Arnold is gigantic and charismatic. Really showing the future action star. Sandahl Bergman is gorgeous and pretty much the epitomy of a Valkyrie. Although she is not a great actress, she did a good job in the film. Mako is amazing in his supporting role as the crazy old wizard. Mako's voice over, especially the epilogue, is just brilliantly delivered. James Earl Jones is well...James Earl Jones. Max Von Sydow as Old King Osric worrying about his daughter plays the sad old warrior, now king, but impotent against the snake religion.
Finally, the soundtrack. What can you say about the Conan soundtrack that hasn't already been said a million times. Basil Polidorous created a score so memorable and powerful that just humming it makes me feel a rush of adrenaline. Polisorous' soundtrack is so closely tied to the image of Conan for me that they are inseparable. The same is true of John WIlliam's score for Superman. Superman isn't superman without that score.
The problem with remakes is that you cannot recapture this. Conan is NOT a great film, but it has all of this talent coming together at one time. Some just starting their careers, others on the downswing, and others who show a spark of talent in this film and fade away. Everything came together perfectly just once for THIS film.
The problem with remakes is that they are usually pushed by a studio as another project to make money. Sometimes it works, other times it fails miserably. There are some good remakes out there. Don't get wrong. The Cohen Bros' True Grit remake is better than the original.
I'll reserve judgement, but 1982's Conan the Barbarian is a high standard to aim for, especially if you're trying to please a fan of the original film.