Good question. It was a 1084M game installation that included 202M of text files and 354M of .wav files among others. I chose such a large archive to stress the limits of the 17 archivers reviewed. I retested WinRK this week just to confirm my numbers and there were no differences.
It is interesting that WinRK did not achieve a good compression ratio on this testset. It has a dedicated Wav Audio compression codec, which usually provides very good performance.
Speed has not been a priority yet in development, only compression performance, so I am not surprised that you could not achieve a very fast time. The next release (v2.2) has some significant improvements in this respect. At a very rough guess it may be able to do your test in under 15min.
The GUI itself was not only inelegant but clumsy, including nonstandard fonts reminiscent of Windows 3.1. If you have the time and motivation for version 3.0 of WinRK, study the interface elegance of such programs like Squeez and ZipZag. You need not go that route, but at the least, seek clarity throughout as WinRAR has achieved. And no one has ever accused WinRAR of being pretty!
The fonts are rendered using freetype, and not using Microsoft's Cleartype. This means that anti-aliased fonts are available on all platforms, and not just Windows XP. They are in fact standard Microsoft fonts. Freetype is also more flexible than Cleartype, although many do prefer the Cleartype result.
It would be great if you could give some specific examples of things (tasks) that you found difficult with the current GUI. GUI design is a very subjective thing, and so the more specific feedback I can get, the more likely I can improve the experience for everyone - beginner and expert alike.
The user interface has been designed to be flexible (eg. the ability to customise the grid columns), and to provide several ways to achieve most tasks. It also provides tooltips on most controls. Also, we intend to improve support for beginner users in future versions, both by supplying a selectable simplified UI, and some wizard based tasks.
Please bear in mind that WinRK is still young when compared with the vast majority of other archivers. It is being developed rapidly, and as such has a rapidly expanding feature set.