This is a nice gadget that works well and I recommend it. I've used it on two different courses with numerous obstacles and these are well mapped. I found all distances to be very accurate when I compared them against the course's surveyed markers. The big plus though is that you don't have to look for those markers plus Sonocaddie provides information that the markers alone cannot provide, like "how far to that creek that runs in front of the green on a par 5 hole" which helps in my lay-up club selection.
The display shows obstacles to the left, right, and in the fairway using easy to understand icons. A large button on the side lets you switch back and forth between an overview display, which shows all the obstacles and distances for that hole, and a close-up display of the distances to the front, center, and back of the green. The display is easier to see outdoors in daylight than indoors under artificial light. The yardage numbers on the overview display are a bit small which requires me to have my reading glasses with me to see them clearly but younger players will have no trouble.
The menus are logical, well laid out, consistent, and easy to navigate. The left small button is used to back out of menus, although a few displays don't include the "ESC" (escape) annotation. The buttons themselves have a good feel to them and always work. They appear to be high-quality buttons that will last a long time.
Sonocaddie comes with a belt clip that is spring-loaded to attach easily to your belt or waistband. It snaps onto the belt clip with a reassuring click and will not come loose. However, the clip itself has some tendency to work its way loose from the belt, but I suspect this is only a problem for those of us who are, uh, fat. A button on top of the clip releases it easily.
It's easy to add a new obstacle or edit one that was downloaded. Just stand at the location you want to mark, select edit, use the arrow buttons to select a position on the screen, select an icon for your obstacle, and then press record. It's easier to do than to read about doing it. At some point it asks you if you want to save the change.
There are numerous courses listed in their database and there is no subscription required, a big plus in my opinion And it holds 20 courses with 18 holes and 6 obstacles for each hole. A comment to another posting indicates that Sonocaddie will map a course for you on request. Course downloads work but are a little quirky. You might have to retry, back out of the download menu and reenter it, restart Sonocaddie, reboot your computer, etc. It's hard to know exactly what to do when a download fails except to keep at it. I was, however, able to download 18 courses without too much trouble.
You can enter in your score for each hole and Sonocaddie will add them up for the arithmetic-challenged It has the par and handicap information for each hole and it would be nice if you could enter the player's handicap and let Sonocaddie calculate the net score but it doesn't do this.
All in all Sonocaddie is a good device and I recommend it. I am not affiliated with Sonocaddie in any way except that I'm an owner/user.