KPS  This app is like those stories of murder-suicides -- a tragedy of epic proportions. The 2.0 "update" not only adds a slow, kludgy interface in place of the old version's sleek and easy one, it erases ALL of your previous feeds so, assuming you can even remember them all, you have to re-add each one manually. Not only is there no provision for keeping your previous feeds, the developers made no provision for exporting them so they are just lost. Gone. Sorry.

This app is just excruciatingly bad.

Absolutely, positively DO NOT buy this app. Even the free version is completely worthless.

If there was a way to rate it zero stars I would do so.  
(Version 2.0)

KPS  An improvement over 3.0.6, but not by much. In all honesty, I finally trashed all the 3+ verions and have permanently gone back to the 2.0 version. The "awesome bar" is just unbelievably terrible. By 3.0.6 it no longer produced useful results at all and I had to resort to typing in complete URLs. At least 2.0.X listed sites visited in a useful order. 3.1 doesn't seem to work any better.

On top of this, Firefox is becoming so bloated that it is starting to look like good old IE in its kitchen sink approach. Sadly, being a Jack of all trades, but master of none is getting old. 3.1 is somewhat faster than older versions, but the history, bookmarks and URL bar all look ugly and don't work consistently (if at all sometimes). More than once calling up history lists no sites at all!

I have a hunch that a lot of this functionality is buried in the preferences and about:config settings, but the more complicated and inconsistent the workings of a web browser get, the less useful the entire app becomes as a web browser.

If I had to fine tune my car every day to go to the grocery store I'd consider getting a different car. Until Firefox stops adding bloat and just WORKS, 2.0 is going to be my new car.  
(Version 3.1b3)

KPS  Crashes consistently any time I try to print to PDF on an iMac 2.16 ghz, 10.4.11. Am able to repeat the crash by selecting "Print" then choosing "Save as PDF" for any web page. Have also experienced other occasional crashes that are unexplained. Obviously 3.0.1 is unstable. I have reverted to 2.0.0.16 and no crashes.  
(Version 3.0.1)

KPS  All the previous versions of this app that I tried simply crashed every time it tried to import PDFs so the fact that version 1.7.9 hasn't just frozen solid yet is an improvement. Unfortunately, the app is still just as useless because it still will not import my entire collection of PDFs. It used to outright crash during import, now it just stops at roughly 13,000 and will not add any more. Since I now have over 60,000 PDFs it obviously isn't even coming close to cataloging them all. The auto-tagging feature is equally useless and failed to produce a good keyword cloud even from the document titles, let alone the content. I still find it easier to locate the document I need using Spotlight or the lowly "Find" feature in OSX.

I've always thought this app had lots of great ideas, but even after many updates I still can't get it to work as advertised. It's like a beautiful sports car that just stops moving after 1 mile -- pretty, but useless.  
(Version 1.7.9)

KPS  This app is beginning to show its age. There are an increasingly large number of movies it will not copy. Obviously the DVD manufacturers are always trying to improve their copy protection technology and they have begun to leave these older rippers behind. Oh and spare me the "all of mine work fine." Yeah, so do 80% of mine, but the list of movies and shows that fail keeps growing.  
(Version 2.6.6)

KPS  As far as I can tell -- you can't. Nice. Yet another blatantly obvious feature that Windows users have had for years and even in 2007 Mac users still have to wait for.  
(Version 3.0b2)

KPS  Yahoo Messenger for the Mac lags so woefully far behind the Windows version that this poor quality update is more insult than improvement. The captcha issue is beyond annoying and the entire program still lacks the vast majority of features Windows users have had for years. While the poor stability issue may be due to it being a beta, the entire effort is such useless crap that the release version can't possibly be worth the effort to download it. Stay FAR away from this dog. Yahoo doesn't give a rat's ass about Macs and this worthless app shows it.  
(Version 3.0b2)

KPS  Simply doesn't work. Assuming a download starts at all (fewer than 1 in 5 do) it just dies off and goes to zero. Have tried it on several different networks in different parts of the country and it has NEVER worked long enough to complete a single download. Even torrents that have hundreds of seeds either fail to start at all or crawl along at a useless 2K/sec for a few minutes before coming to a complete stop.

Nice idea, but a complete waste of time in implementation. Yeah, I know some people get it to work, but I've tried 3 different versions on several completely different networks and it has NEVER once lived up to its promise. Obviously it could be some sort of configuration issue, but the app gives no useful diagnostics, no real way to change settings that actually help and no way to test what is happening. I've tried it on several different computers as well and it's always the same -- all hype, no function.  
(Version 4.27.2)

KPS  Does it still crash with collections of more than a few thousand PDFs? Never did get it to index my collection of about 16,000 PDFs even a single time. Every version I tried collected a few thousand then crashed.  
(Version 1.6.4)

KPS  As of 1.2.4 still crashes with large collections of PDFs. Unusable for anything other than modest numbers of files. Obviously can't even try the various features if it isn't stable. Should still be considered beta software. Now that it is no longer free it is an even worse value.  
(Version 1.2.4)

KPS  Apparently unable to handle large PDF collections. I have about 6000 PDFs and Yep crashes on all 3 different Macs I have -- Intel iMac, G4 Powerbook and G4 desktop. Tried loading the PDFs from internal drives, external drives and even a DVD and the program always crashes at about 1800 records making it useful only for very modest collections of PDFs. Unfortunately, people with 99 PDF files don't have much need for a storage system for their PDFs! Have tried several versions of Yep and all crash during the scanning process, including the newest version.

Conclusion: Nice toy, but useless for real productivity. Does not even work at all for the people who need it most.  
(Version 1.1.2)

KPS  Worthless waste of money. App is amateurish and looks like it was built in 1989 on a Mac Classic. Menus are cryptic and don't follow Mac conventions. Strange "Will not save library" messages crop up and ruin hours of work.

Absolutely, positively do not waste your time on this class project from a bunch of third graders.  
(Version 2.2.1)