Yes! You can watch their status if they have opened the itinerary email and/or download the Trip Plans app. You can see this by clicking on the trip itinerary in your active trips list:
You can also go into the itinerary builder, press ...More on the top toolbar and then press People and you will see each person listed and it will tell you if they have opened, clicked, or if there has been no invite sent to the client yet.
What each symbol means:
When viewing if a client has viewed the itinerary from the trips page (from your main dashboard), you will see symbols next to each client name. The circling arrows symbol means that the itinerary email is Pending, meaning that they haven't opened the email yet. The mobile phone symbol means that they have downloaded the Trip Plans app. If they have a web circle symbol next to their name, that means they have not downloaded the Trip Plans app and they are viewing the itinerary via the shareable URL.
Once they have viewed it, you notice an eye symbol which means that they have Viewed the itinerary.