(1) See loading-of-services-php.txt. "Configuration" -> "IT Services" tab takes a very long time to load. It can be seen in the debug log that the frontend generated a 3 MB SQL query listing all the triggers. Similar issue can be observed in other pages related to IT services.
(2) See editing-an-it-service.png. The checkbox marked with an arrow is a no-op, i.e., it does not have any effect.
(3) See editing-an-it-service.png. The button marked with a circle says "add", whereas typically we use capitalized labels.
(4) See triggers-in-hosts.png and triggers-in-it-services.png. In the first case, triggers with severity "Not classified" are displayed on a gray background, whereas in the second case they are displayed on a green background.
(5) See triggers-in-it-services.png. When this pop-up first launches and has no groups and hosts selected, the trigger list is empty. When you select a host, it shows the triggers for that hosts. Then, unselect all groups and hosts. The popup still shows the triggers for the last selected host.
(6) See config-of-it-services.png. If we try to link "My Test Service 2" (which has child services) to a trigger, the frontend does not display any warnings or errors. It should. Probably, it should also display a warning when we try to create a service as a child of another service, which is linked to a trigger.
(7) See config-of-it-services.png. Might not be a bug, but still drawing your attention to it. Should it be allowed to create several services with the same name?
(8) See config-of-it-services.png. The message to be displayed in the green strip is passed as a GET parameter. Other scripts do without.
(9) See temporary-popup.png. When deleting a service, a temporary popup is displayed. It exists there for some time and then disappears. Also, the children of the deleted service become children of the root service. Maybe, they should become children of the deleted service's parent? Or, maybe, the children should be deleted altogether?
(10) See monitoring-it-service.png and till-column.png. If we click on the green SLA strip marked with a cross in the first picture, we see the second picture. The "Till" column is too wide.
(11) See monitoring-it-service.png and yearly-availability.png. If we click on the green SLA strip marked with a cross in the first picture, and then select period "Yearly", we see the second picture. It shows availability for years 2005-2010, even though we only started running Zabbix in 2010. It should probably be made more intelligent.
(12) See monitoring-it-service.png and no-permissions.png. If we click on "Show" marked with an arrow in the first picture, we see the "No permissions!" error in the second picture, even though we are logged in as "Admin".