I was very excited when Unison 2 came out and bought my upgrade immediately. If you need to actually browse or search through newsgroups (as opposed to simply downloading massive queues of NZB files), there aren't many options on the Mac, and the interface was decent.
The biggest problems with the first version (which was around for about 5 years, I think!) were that it was ridiculously slow at downloading compared to every other newsreader on Earth, and it had a bad habit of crashing or just stalling randomly and being unable to resume. Transmit isn't the fastest FTP client, either, but it is at least reliable and has a decent interface, so many of us use it. Panic's developers seems to simply not be very good at data transfer.
Unison 2, unfortunately, is not much of an upgrade after such a long wait. It is faster, but still nowhere near as fast as most any other contemporary newsgroup downloader. The interface is still OK, but it is nowhere near as usable as the guys at Panic seem to think it is. For example, the "Transfers" section, which shows current transfers and allows you to rearrange or remove them, is at the bottom of a scrolling sidebar. At the top of the scrolling sidebar is the Newsgroups section. So if you have more than a few newsgroups, it is very likely that the transfers section will simply scroll off the bottom of your screen, and you'll have no idea how to adjust downloads. It would make far more sense to have the transfers section be pinned similar to the "activity" panel at the bottom of the sidebar in Mail. An even more exciting UI challenge is that if you go to the "Window" menu looking for a downloads window (as you did in Unison 1), you'll find the Activity window that looks like it should be managing downloads, but does not enable you to interact in any way with the progress it displays. Mail has a similar separate activity window showing individual operations, but it, like a well-designed program, has a cancel button next to every progress bar.
The truly spectacular failure of Unison 2, though, is the complete inability of the program to mark messages as read and hide them. A newsreader without the capacity to mark messages as read is like a toilet that can't flush. Newsgroups get thousands of messages a day, every day, yet Unison 2 has screwed up the most fundamental way of managing that flow. The program has a menu item and a toolbar icon for "Mark as read" and "Mark All Read", but they do, quite literally, nothing. There is another menu option and toolbar button to "Hide Read", but it, too, does absolutely nothing.
The only way to keep from having 8 million messages in every newsgroup window is to delete them all after you've caught up. Hope you don't ever need to search for something you read yesterday! This has been broken since Unison 2.0 launched, and is still broken months later. I really don't think anyone at Panic gives a damn about this program.
Certainly for the premium price they charge, I would expect at least basic functionality to work.
The good news is it doesn't seem to stall or crash as much as Unison 1. It's a shame that is really the best thing I can say about this upgrade, the guys at Panic should be embarrassed.