I'm a full-time Ra player, and have just started messing around with Isis. Her main advantages:
1) More pop
2) God-power blocking monuments
3) Cheaper upgrades
4) Awesome archaic age power. By far the most important resource for Eggy is gold, and that's what Isis's archaic power gives you -- lots and lots of gold.
(5 - not an innate power, but Ancestors/Eclipse gives you an instant army that can fight off a big attack on your flank, take down an enemy town center, wipe out your enemy's military buildings ... basically, the equivalent of Earthquake, a Mythic age power, as soon as you hit Heroic)
With any two of the above, she would be impressive. With all 4, she is ridiculously powerful. In my ideal world, they'd take #1 or #3 and give it to Set, and give Isis the cheaper migdols that Set currently has. This would make Set better and knock Isis down to the level of the other two Eggy gods.
Of course, in a perfect world I'd also like to see Ancestors not be affected by Eclipse (but perhaps be a little bit stronger than they are now, non-Eclipsed). This would make Isis a bit more manageable in Heroic, and also make her more flexible -- there would be compelling reasons to choose gods other than Bast/Nepthys.
I'd also like to see Archaic powers shifted a bit. Ra would get Vision, Isis would get Rain, and Set would get Prosperity. This makes more sense too, considering the gods. Ra is the chief Egyptian god, looking down from above ... therefore he can see things that normally can not be seen. Isis is the "mother goddess", the goddess of life. Providing food should be a natural. And Set is the god of death and the underworld. Gold is retrieved from underground.
If the above changes were made, Eggy would still be very strong but would have a much better balance among the three gods.
[This message has been edited by regular_gonzalez (edited 12-12-2005 @ 12:30 PM).]