Still the best Japanese-English dictionary for the Mac…but I'm sad to say this is mostly due to the lack of any viable alternative. While JEDict is packed with useful functionality, the user interface is quite a mess, and it's really starting to look old and broken compared to all the other apps I use on a regular basis.
Lately I've taken to simply using the built-in Dictionary app in OS X, which actually has very good Japanese-English dictionary (and an excellent Japanese-only dictionary, if you can read enough Japanese to use it), and I only turn to JEDict when I need some feature other than looking up words (like looking up individual characters, or compiling a list of words via the userdict).
I understand this is the work of a single developer who most likely has a day job or some other full-time occupation, and I think he's done us all a great service by at least maintaining it in a mostly-working state through all these years and major OS upgrades. But this app needs a complete teardown and redesign of the entire user interface, and I think it's going to take at least one professional UI/UX designer to pull it off. And unfortunately I also think this is such a niche product that Mr. Kurkin can't really be expected to hire a pro to sort this out properly.
What I'd really like to see is a Mac version of the excellent "Japanese" iPhone app (by "codefromtokyo"), which comes awfully close to matching most of JEDict's functionality, and does so with a fantastic, modern UI that is a pleasure to use (something I really can't say about JEDict).
For the time being, I'll be sticking with JEDict, since it's still the best tool (despite its many shortcomings). But I really hope to see a better alternative, someday.