I have used the Atmel-ICE with a few different AVR microcontrollers along with the Atmel Studio 7. It works well but I have had a few small issues with JTAG debugging from Atmel Studio, usually I just restart the debug session and things work. Definitely the best tool I have found for AVR JTAG debugging. For more information see the the Atmel-ICE product page. The link to the online user's guide on that page is currently broken, I will add it to the comments if I can find a link. Here is the Atmel-ICE User Guide at DigiKey. The Youtube video Atmel Edge With Paul Rako: Debug 102 shows and unboxing and goes over the basics of the kit. The video is embedded below (no pun intended).
