Just at a glance, a few things strike me...
Phobos doesn't typically use classes, seems to prefer flat functions. Are we happy with classes in this instance?
Use of caps in the filenames/functions is not very phobos like.
Can I have a post-de-serialise callback to recalculate transient data?
Why register serialiser's, and structures that can be operated on? (I'm not a big fan of registrations of this sort personally, if they can be avoided)
Is there a mechanism to deal with pointers, or do you just serialise through the pointer? Some sort of reference system so objects pointing at the same object instance will deserialise pointing at the same object instance (or a new copy thereof)?
Is it fast? I see in your custom deserialise example, you deserialise members by string name... does it need to FIND those in the stream by name, or does it just use that to validate the sequence?
I have a serialiser that serialises in realtime (60fps), a good fair few megabytes of data per frame... will orange handle this?
Documentation, what attributes are available? How to use them?
You only seem to provide an XML backend. What about JSON? Binary (with endian awareness)?
Writing an Archiver looks a lot more involved than I would have imagined. XmlArchive.d is huge, mostly just 'ditto'.
Should unarchiveXXX() not rather be unarchive!(XXX)(), allowing to minimise most of those function definitions?