Don't worry, nobody is saying trackpads in general are bad.
actually, my favorite input device has always been a nice substantial trackball like Kensington's Expert Mouse, and i did say trackpads in general were bad for years; i never liked them at all. but i've realized while reading this thread that i think the trackpad on my 17" Unibody MB Pro has finally changed that. i share many people's frustration with spontaneous, unintentional resizing of screen elements; it's happened to me many times in Safari, and a few minutes ago i somehow managed to make all my desktop icons smaller by just moving my fingers on the trackpad, which is especially baffling since i can see no option that corresponds to this behavior in the Trackpad pref pane. i had to open View Options and use the slider to put my icons back to the size i like them at. and trackpads in general suck for applications where you need a lot of control; i couldn't think of using a trackpad (or a mouse, for that matter) for fine-detail image editing, and when i used to play World of Warcraft, having to use even my MB Pro's trackpad was a one-way ticket to death. but for general computing, i must say i think the MB Pro's trackpad has finally changed my mind about trackpads. mostly.
can you thumb click and drag stuff around with these new trackpads?
yes you can. you can click either by tapping the surface of the trackpad, or by pressing down on the trackpad like a regular mechanical button - because in addition to being touch-sensitive, the whole trackpad *is* a regular mechanical button.
so to thumb-click and drag stuff around, you press down on the trackpad with your thumb until it clicks and hold that while your finger uses the pad's touch-sensitivity to drag.
as far as your hand is concerned, it's identical to doing the same thing with a trackpad that has a mechanical button at the bottom; it's basically just that with this trackpad, there's no visible delineation between the trackpad and the mechanical button, because the two are the same.