Yeah, definitely bummed at some of the hsows 
coming out to be CG. Like Fruits Basket ::sigh:: 

The easiest way to tell, though, is that CG anime 
has a different feel and look to it. The 
animation isn't as smooth, generally...it tends 
to be a bit more blocky. There's also less 
movement. There's an increased use of (sometimes 
cheesy) digital effects, such as types of wierd 
blurry fade-outs or odd swirly blood, or in 
Saiyuki's case, youkai exploding into 
computereized polygons -.-;; The colors and lines 
also tend to be more sharp...there's a distinct 
lack of linework for value. Everything is defined 
by color, and the color doesn't blend nicely, 
it's just kind of...plopped there, in shapes. As 
you can tell, we have a long way to go before CG 
anime looks as nice as cel-animated anime ^^;; 
(although it is getting closer, in some cases)

-Misha