IMO, absolutely. Modern sun sign astrology uses a lot of the same vocabulary but has tossed a lot of the metaphysics from which the terms derive... so it doesn't go much further than adjectival perkiness. Go to the source.
To tackle the astrology in the Thoth (or really any GD deck) I think a very helpful approach is to think about the
worldview bound up in it. Unlike Qabalah, astrology explicitly formed the underpinnings of LOTS of european arts and sciences... esp. metaphysics, doctrine of the humors, and thence temperament.
I spent a lot of years dismissing astrology because I associated it with the fluffy horseshit into which the "Queen of the Sciences" has devolved. Just keep reminding yourself, newspaper zodiac astrology is NOT what's on offer in the Thoth. Don't worry too much about signs, focus on the the planets which are the power SOURCE. Whenever you look at a modern book on (psychological) astrology keep telling yourself: planet NOT sign, planet NOT sign. Look at Dignity and Reception.
John Frawley's
Real Astrology is hilarious and eye-opening. Ditto Olivia Barclay's
Horary Astrology Rediscovered. Lehman's
Classical Astrology for Modern Living is a little hardcore if you just want an intro. But it's awesome. One of my faves is Geoffrey Cornelius'
Moment of Astrology, which is a beautiful book about divination in general, but Astrology specifically. All of those authors are working traditional astrologers that have worked hard to restore the rigor and vigor to the discipline. Incidentally, C.S. Lewis'
Discarded Image is a terrific attempt at a glimpse of the medieval worldview, though not focused on astrology. The Skyscript website has wonderful articles and books available. I posted a list of links and books over in the Golden Dawn tradition subforum:
http://www.tarotforum.net/showthread.php?t=96946&page=3&pp=10
The rough part is, most GD scholarship focuses on Qabalah. There aren't a lot of good astrology resources that are easily found. But the material is out there.
Let me know if I can help in any other way.
Scion