My first impression is that of beauty and tidiness. I love (need) clean, beautiful interfaces if I'm going to work happy. And this one is among the best I've seen (and felt). The icons are clear and representative. The palettes are easy to turn on and off, so you don't need to have everything open at the same time. And then there's the Lagoon: a lovely corner with quick access to all you need when you're cruising, which is also fully customizable. The Quick Tour window shows you the essentials without having to say a word. Something most people (who hate reading manuals) would appreciate.
As usual, I'm drawn to try the brushes that come with the program first, to have a feel for what the engines are capable of. There are plenty to try right off the bat, and even a lot of free brush sets you can download right from the SketchBook Extras window. The brush engines are not the most crazy complex in the industry, but they do the job and they're pretty versatile. Something I liked a lot is that no matter how much or how fast I was making marks, my computer didn't get as hot as it does with other programs. Moreover, there is almost no lag at all. Great! Another thing I loved is the Brush Library. Everything about it is beautiful: from the looks to the way it works; simply and efficiently.
The more I used it, the more I fell in love with the UI. Love, love, love. But a great UI is worthless without ease of use. And here I'm impressed again. Multi-touch control like pinch and zoom and rotate worked from the get go, without effort. No painfully configuring anything, like in other software.
The brush and color pucks were such a great surprise for me, I felt like a kid at Christmas when I saw them working in the Quick Tour examples. I liked them so much I don't think I'm going to be able to work without them ever again!
When you're using the eyedropper tool, hold the click and a zoom of the area you're clicking on appears, to help you pick with better accuracy. I love this!
Everywhere you look or click, there's good implementation of controls and design, which makes me feel I'm using the equivalent of a high-end car or device, where the attention to detail and quality is par none. I think this, in turn, makes you want to come back and use it again and again.
The stroke assistants are there to make your life easier and they work like a charm. The guides like the ruler, ellipse and French Ruler are so easy to work with. Not to mention the symmetry tools and perspective guides, which are amazing! The perspective guides have 1, 2 and 3 vanishing point modes AND a fisheye mode. The symmetry tools include not only vertical and horizontal, but radial symmetry as well. Everything in this program is so intuitive, so easy to use.
In addition to the color editor and the color puck, there's also a Copic color library, which most illustrators should know. When you select one color, you are shown its complimentary as well, making your life easier once again. You can also make animations with the flipbook feature. So you have everything you need to make your ideas come to life and feel very comfortable in the process.
SketchBook is not intended to be the monster piece of graphics software that does it all (it's implied in its name), but its strength resides in its amazing usability and attention to detail when it comes to user friendliness. I've tried a lot of graphic programs and I can tell you without a doubt I found this one by far the most comfortable to work in. So if you're looking for a true digital sketchbook, you will definitely love this one.