However, if you can get over all that, it actually works quite well for keeping your addons up-to-date. It scans my directory of about 100 addons pretty quickly and fetches information on any release-quality upgrades (or whatever level of upgrading you set as your preference) that are available, downloads and installs them efficiently, and lets me get on with my playing.
Another feature I find convenient is the ability to handle "install via Curse Client" web links. Being able to install a mod with one click from a web site is nice, especially for an addon junkie like me. This feature does not appear to work if you click a link while Curse Client is not open. It does launch the client, but the addon never downloads and installs (despite the presence of a progress bar).
On the other hand, there are still some things about Curse Client that do not please me. Foremost is its unnecessary invasiveness. I don't want an icon in my menu bar whenever I have the program open (at right), and I don't want Curse Client to start up every time I log in; I just want to update my addons every so often. I can change the start-at-login behavior from the preferences, but the default (to start at login) is wrong. There isn't any way to remove the useless menu bar icon that I know of.
I'm also told that the Windows client by default installs an addon that mines your data and uploads it to Curse, which is unacceptable behavior, but this isn't the Windows review, so I'm not going to say any more on that point.
The icons, which seem to be the primary interface for most actions in the client (checking for updates, installing addons, removing addons), are less than intuitive, and are certainly non-standard. I would like to see more standard Mac OS interface elements in a future version. And what's with swoopy-arrow meaning "update all addons"? I'd like to see multiple overlapping arrows, or something like that.
There is one big functionality issue. For a substantial minority of mods, even if they're on the Curse site, they turn up as "unidentified" and have to be re-installed via Curse Client before you can update them automatically. I don't know what the deal is with that. And of course mods that aren't on Curse don't show up in the client, but there's not much to be done about that.
So, Curse coders: if you can fix the non-sensible defaults, get rid of the menu bar icon, improve the icons, solve that wxWidgets error, stop cluttering up my screen with progress bars that should be in the main window, and figure out why some addons aren't being detected, you'll have a great client on your hands. Until then, it does the job, and that's really what matters.
Download Curse Client at Curse