This is not an easy hike. But it's an awesome hike, for sure. If you aren't an avid hiker, my main piece of advice is to STRETCH YOUR CALVES before you start. Seriously. You'll thank me when you don't have debilitating cramps. And bring water, you're going to be huffing and puffing.
I entered at the new trail head from the north. There is quite a large parking lot, a small educational area, clean bathrooms and NO RUNNING WATER. This is important to take note of if you plan on filling your water bottles at the gate.
There are many steep switchbacks and several beautiful scenic spots. If you're into rock climbing, there are a handful of locations here for bouldering.
Getting to the Thumb feels great emotionally, but for me, it was a bit anticlimactic. There is a better scenic spot about .5 of a mile prior to reaching it where you have a beautiful panorama of the McDowells.
High heeled shoes may give you great calves, but Toms Thumb will give you a great butt!