So many things are going wireless, and so many devices are becoming battery powered, that power consumption is a very important thing. AVR has a new marketing term called picoPower. PicoPower is a new thing from AVR, and it leverages all the previous technology we have in lower power, and adds to it. One of the big differences with picoPower versus the other AVRs was the power save mode. It has gone and completely redesigned the 32 KHz oscillator to have a zero-power 32 KHz oscillator. That's allowing 0.6uA in power save with that oscillator running. Finally, in full run mode, it can do as low as 220uA per MIP in full active mode. These devices run from 1.8-5.5V. The 1.8V device is a true 1.8V device. That means that everything works at 1.8V. The designers can write to Flash, SRAM and EEPROM.
Easiest fix, IMO, is to add another signature entry into avrdude.conf and boards.txt.) Once it has your bootloader on it, it acts exactly like an Uno.