Some Suggestions I have for the developers that would probably make it a 5 star app is to possibly add some type of Photoshop like layer feature or even some type of animation like timeline, so you could switch back a forth between different drawings or build on top of existing ones. So overall for my purposes it is a wonderful tool. pressure sensitivity effects for brush sizes and opacity. I use a wacom tablet while working and Ultimate Pen's tool work great with it i.e. I am an illustrator/Design and I am currently learning 3D animation ,and this app has become an essential part of my workflow while animating, studying video reference, and just jotting down quick notes. I'm running Lion on my MacBook Pro and Ultimate Pen has been working fine for me. If that does not resolve the issue contact Apple Support directly.
Note: If you experience a Hash Mismatch error when trying to update from Ultimate Pen v1.5 Apple recommends that you delete the App from your computer (should be in the Applications folder) and then launch the App Store and re-install the app. NOTE: Currently Ultimate Pen does NOT work on top of Keynote or PowerPoint while they are in presentation mode. Ultimate Pen's unique Click-Through Mode makes your drawing float on top of the screen even as you access and use other applications.
Once you've finished drawing, take a full screen screenshot, select part of the screen and grab only that, or copy your drawing to the clipboard for use in another app. Use Ultimate Pen with a mouse, or, for even more control, use Ultimate Pen with a drawing tablet to take advantage of the tablet’s pressure sensitivity to modify the thickness or opacity of your drawings. You can add notes, draw shapes, make comments, or paste illustrations directly onto the screen. Ultimate Pen creates a full screen, transparent window on your computer screen allowing you draw on just about anything. Ultimate Pen is a favorite among educators who use its drawing and highlighting features to actively engage students and to emphasize lecture concepts. Think of Ultimate Pen as an incredibly easy way to annotate and doodle on your computer screen – and you don’t have to buy any special hardware. Ultimate Pen is unique, creative software that allows you to draw on top of most applications.