I havent bought mine from AmiKit, but I own a prebuilt Sam440ep flex. The machine was easy to set up. It runs some classic 68k software like Turbocalc and Final Writer and TV-Paint, but fails with other like DeluxePaint or ComicSetter.
The box runs reasonably fast, but you have to be careful what you plug into the USB-ports. Most USB-HW has no problems, but not every thumbdrive will work.
Bootup is a bit slow at first, but once Kickstart is loaded reboots are lightning fast. I have blogged about some of my experiences. My blog is here on Amiga.org.