The AmigaOne is an excellent machine as long as you have realistic expectations. AmigaOS 4.1 runs beautifully on it, but as it only has (officially) a maximum of 800MHz G4, you shouldn't expect to be decoding BluRay or anything on it.
The AmigaOne SE is a bit ... idiosyncratic, shall we say. It has some definite flaws, which limit its usefulness (particularly the fact that you're stuck to the on-board graphics with only 32MB graphics RAM). The AmigaOne XE, however, gets a lot of undeserved bad press. Look after it, and you can really enjoy an XE (I enjoy mine!). There are still problems, but almost all of them you can get round and have a good, stable system.
In other words, the SE is probably not worth it - spend the extra and get a Sam - but the XE can be well worth it if you can find one.
