I found that it works pretty well and is very easy to use. In my case, although, after some time, I decided to return to my old scheme, which rarely uses DI in unit tests, if I do not test something functional. I found that all the extra features that AtUnit provided were simply not used in my situation.
In cases where I use Guice in tests, my unit test extends class AbstractModuleand I initialize Guice, etc. manually in my method @Before. I believe that using AtUnit here would be pretty much the same, except that all of my stuff will disappear manually.