I think I wrote something about this application last year. Acrylic Times is a very slick RSS client application that faces huge challenges in spite of being a beautifully designed application.
1) It's a license in an era when people have an expectation of free.
2) The RSS client market is not growing and it's not that big to begin with. RSS client apps (hosted or installed) tend to appeal to a very niche market (tech centric, high income/education, male) despite being available as mature product offerings for many years. RSS as a product/technology name is a significant barrier in itself, hell you might as well call these apps "cancer" because for the mass market it's just as appealing.
3) The fundamental weakness in the user experience is that you have to proactively manage content sources. This is a huge turnoff for me because my OPML file is a mess and I just don't want to take the extra steps to subscribe to content sources I find on my own...
Nobody is doing content discovery at the source level really well, but balancing content relevancy to user behavior within defined sources is coming along nicely. One of the most exciting apps in this regard is Feedly, I absolutely love what Edwin and team are doing but I don't think of that as an RSS app... it's an application that takes advantage of RSS for content but RSS is just one content source.
Another example of this is the PostRank Twitter Newsroom, which builds on extensive experience measuring RSS feeds and applies the same ranking mechanism to twitter streams. This is just one more example of how broadcast content is converging with social recommendation. The next frontier is bringing email into the mix with web intelligence derived from social networks and content.
At any rate, check out Times and give it a test drive.