It depends entirely on the JRPG for me. I absolutely cannot stand the average JRPG fare, which has been explained thoroughly by previous posters: cliche, battle system etc. However, when a JRPG is truly done right, they are absolutely brilliant. Because of the linear nature of JRPGs, there is less focus on character development and exploration and a greater emphasis on story, which means that it is required that a JRPG have a great story for it to be a great game, at least in my eyes. In order for me to enjoy the experience, I have to be attached to the characters and set pieces and I should be compelled to want to see the story progress. JRPGs are a great medium of storytelling because the developer can fine-tune the linear experience exactly how they want as opposed to WRPGs which are far more open-ended and exploration focused(Most of the time). So in short terms, JRPGs have a disadvantage when it comes to gameplay and character customization, but shine when it comes to storyline and immersion. The catch is the gems of the genre are truly diamonds in the rough, as many JRPGs simply have no appeal due to a stupid and recycled story and characters.
I still prefer my western rpgs on the whole, but when a JRPG catches my eye, its worth a try to see if its a winner.