The widget gives me a calendar for the home screen that shows several weeks (I have it configured to three weeks.) There's a little color coded bar at the top of each date that tells me I have an appointment that day, and the color tells me which calendar so I know if it's business or not. If I tap the day, a little sub window pops open telling me the details of that day.
Tapping the first or last day advances the three week window, nice although it means that when I want to view the appointments on the first or last day I have to advance it, THEN view them.
I cannot use this to view the details of an appointment, at least I haven't seen a way to do that. So I do use it in conjunction with the built-in calendar. What's been working really well for me is an agenda view of the built in calendar which shows me just a bit on the home screen, then this widget showing me three weeks on a side screen. I have to go back to the regular calendar view to get details, but at least I can get to everything between the two of them - and this does give me a great overview at a glance.