Not an owner, but a fan.

Don't own a 5124J, but this is a watch that's really growing on me. It's a informal/casual business watch that has a soft side to it. I'll bet it's comfortable to wear on the wrist because of its curved case-back.

I am a small fan of art-deco inspired pieces, and both the 5124J and 5124G are very beautiful watches. I normally see the 5124G at ADs and it's a stunning watch in person, although fairly large on the wrist. I would consider this watch to be one of those super-simple and elegant watches that Patek has to offer.

Movement-wise, the 25-21 REC PS is a true square movement (actually shaped as an octagon if you look at the plate itself), and it beats at 28.8K while still maintaining a 44 hour power reserve. Manually wound, and an utter classic. Compare this movement with the 215 PS which is the round movement found in the 5119, 5196, and (a new favorite) the 5116G (with enamel dial) and you'll see many similarities across the board.

So, the question is, go for a 5124 or for a 5116/5119/5196.