I tried it when it was bundled with my K-7 almost 2 years ago, but it was so bad that I threw it away after a day. The user interface was downright nonsensical and it kept crashing a lot.
I have been using
UFRaw and
The GIMP ever since. Both are free but take a lot of getting used to and have their limitations.
There are really a lot of programs to chose from and I would say none of them will immediately give you better results than others. You will have to try a few and see which one works best for you.