I'm not a fan of the popup list add/edit dialogs to add content in 2010, is there an alternative UI, or is this something I have to get used to?
The only scenario which gives the option of an alternative UI is the case where the sites were upgraded from WSS 3.0/SharePoint 2007, and you make use of the Visual Upgrade capability. This allows you to preserve the earlier look and feel to allow you to transition more slowly e.g. to give time to make any required changes to custom master pages.
However it is meant only as a transition aid - you technically could stay in that mode forever, but users would be missing out on functionality exposed in the new UI e.g. async page refreshes when working with items in a list.
So you're going to have to get used to it, but as well as having much fewer postbacks/page reloads (as mentioned), the new UI brings other benefits. Most folks feel the "popups" are an improvement as you stay in context for what you were doing (and return to the 'greyed out' page once the dialog has closed). In SharePoint 2007 you frequently had to 'navigate back' which wasn't the slickest user experience. The ribbon (very contextual), status bar and notification area are other UI improvements.
P.S. They're technically not popups anyway, it's an IFrame loaded into the current page :)