Since there's a couple Bilstein threads, I'll put this post in both for search purposes:
Well, I got the shocks in on Friday. Put the fronts in Sat morning, and went for a long drive to see what the impact of front only. Front was much more controlled, and less "2nd" bounce form hitting the bumps, as stated from guys above.
But, as was suggested by FirstDiesel
, the rear felt REALLY squirly. The boucyness in the back was very pronounced, since it lacked the same control that the front now had. So, this made me feel very good that I got all 4.
Next, pulled the rears, only to find that one of them was wasted. So, this explained the REALLY significant difference noted, but still justified the new rears. Put them in, and went driving around again - very noticeable improvement from the rear.
I think ride is a little stiffer, but this is partly from the lack of "wallowing" that exists with the stock shocks. Overall, big improvement as everyone else has stated. I would have to recommend that anyone replacing the stock shocks, do all 4, as was recommended by others.