What do you like best?
As a fine artist I found Corel Painter to deliver a very similar experience to the traditional process of drawing and painting. It can emulate everything you need to fool others into believing your work is a photograph of an actual piece. I recognized the potential of tweaking my brushes to deliver a realistic feeling, so I spent the time watching tutorials to understand how each setting affected my brush performance. It takes training to get the most out of the program. As a beginner or casual user you can still make great artwork with no training whatsoever.
My favorite two features are the unlimited symmetry axis tool and the tracing pictures tool. These two helped me saving time when running with creative design projects and illustration work.
What do you dislike?
Like with any other software there are always some technical limitations. Probably those limitations will be fixed in upcoming versions.
In a sense having a lot of control over your dabs is a great feature for the proficient user, as a beginner though I found the interface and all these controls to be overwhelming and sometimes the tab titles a little confusing.
I would like to see hinting bubbles where I can read what each feature does. That could help a lot a beginner to figure out what are all these functions for. At the time when I started using this program (around version 10), they didn't have any visual help. I worked a nice illustration and I used a bunch of different brushes, it resulted that one specific brush pattern couldn't be saved in my jpg, so I had to figure out a way around to show that layer.
Recommendations to others considering the product
I definitely recommend to other digital artists to learn how to use Corel Painter, specially if you enjoy reproducing the natural texture and look of traditional techniques. Although before jumping in and start using it I would advise to spent some time watching tutorials, learning the logic within the user interface because some things are different from what you would expect. I came with a background on Photoshop and I was expecting a similar response, which I didn't get most of the time. Even though they look very similar, Corel Painter has its own nature and it is important to understand it, specially if you get frustrated easily.
Learn the limitations ahead of time, so you won't waste time in the middle of a deadline, and keep in mind that there is always a way around it.
What business problems are you solving with the product? What benefits have you realized?
For a quick digital illustration or turning a photo into a digital painting this program is the most robust, and those are the main uses I gave it. I'm a fine artist and I can work faster when I get the chance to use traditional media without having to waste time scanning and fixing my image. I was able to paint 13 illustration covers for a calendar in only 2 days using mainly the tracing and symmetry axis tools.
The problems I solved with it are usually constrictions in time and the delivery of an artistic piece or design.
The benefits so far using it for projects is that is very similar to working with traditional materials and getting what you want from it becomes 2nd nature due to your previous experience with the traditional media. In other words: you will be able to understand 70% of the tools because of how well it mimics the traditional media process.