I'd go along with the book's assumption that Prince Of Egypt (nice to see it getting recognition!) was their first film, which it was.
POE was the catalyst for DWA right from the start, being Spielberg's suggestion. PDI was initially brought in as a production partner for the CG side of things, and ended up making Antz as a separate film but, at the time, the deal was that DreamWorks SKG would "present" the PDI films, like Disney does with Pixar and Fox does with Blue Sky.
So POE was DreamWorks' first animated film, since it was in production first and was their first direct film. Antz was eventually made faster and released a few months before, but really this was like Mouse Hunt from a year or two before: an example of DWs presenting a production (albeit one they had generated in-house).
It wasn't really until the tradigital animated films (El Dorado, Spirit and Sinbad) flopped and DWs decided CG was the future that DWs bought up PDI outright and became the wholly integrated DWA. Retrospectively, they include Antz as one of their films (correctly, I think, in the way Toy Story is now a Disney-Pixar film when originally it was a Disney film animated by Pixar), and I suppose technically one could say it was their first release.
However, I would also offer up Mouse Hunt as at least being a hybrid (along with Small Soldiers) in that same list if we wanted to get too completist about things, so really the reviewer is right here, and POE should be recognised as their first film. That said, in this CG world, Antz probably makes the better case since it's more in keeping with current trends, and although there's no confirmation one way or the other it does seem the King Of Dreams DTV has been forgotten, although this could be to concentrate on theatricals.
Speaking of which...I wonder if it includes a bit on First Flight, an absolutely adorable short made in the early 2000s that has never seen a public release. I don't know if DWs routinely makes in-house shorts, but that one really does deserve a release since it's so cute!
Moreover...this looks like a great book to nab if I see it around - thanks for the head's up, Vi!
