The pre-existing home sales look to be running at about the same number they have been during the past year - maybe a little higher, but I have not noticed a large increase in the number of "for sale" signs in the neighborhood. I'm sure there is a little bit of money problems at play.
However, there is still a lot of new home construction going on in a couple of the new phases, and there is a new phase that is just beginning to sell closer to 121. I think it is a sign of strength of the community that homes are still selling here.
To address Big G's points:
1) Taxes - the tax rate is slightly higher here (I think we were at 2.5% this year), but the taxes for the new districts that are created as new phases open are borne by the residents of those districts, not the existing ones which are already seeing decreases in their water district tax rates.
There is a 0.5% fee on the sale of each house, but this money is used for two purposes - funding for the Lewisville ISD schools that serve CH, and scholarship money for college students that are residents of CH. The college scholarship program pays $2000 per year per student, with no requirement except a B average. The program pays a maximum of $10,000 per student, so if you have kids that are nearing college age it is a *very* good benefit. If your house is $400k, your fee on sale of the house would only be $2000 - so you can see the payoff in this case.
2) Schools - Lewisville has some very good schools (I've never heard them called a red-headed stepchild district before

). Castle Hills elementary is an Exemplary school, and I believe the new middle school (Killian) is Recognized. Hebron High School is shared by CH, Plano, and Frisco, and seems to be well-regarded. The Flower Mound schools are also in the Lewisville ISD, and I don't think I've heard any complaints about them either.
3) Foundation - we definitely have a high concentration of clay soil in CH (along with a lot of other areas in Dallas) and there were some publicized issues with houses in one area back in the early days of the neighborhood. The cause of the foundation issues in that case was a ruptured water main that flooded the clay substrate and it was confined to one custom builder that has not been building in the area for many years. Builders have been working in this area for a decade now, and do full soil testing to determine what is necessary to prevent shifting. Regardless, I agree that you should have an independent engineer (not an inspector or foundation company) do an analysis (that will probably add about $400 to your costs, but is well worth it)
I have seen several people sell their first house in CH and upgrade within the neighborhood in the two years that I've been here, so there is some of that going on.
The developer has done a great job of adding amenities for the residents and creating a feeling of community. I assume you already saw the new community center in the Village Shops that has the kids splash fountain and concert stage? I think this is a great area with a lot to offer for families.