We entered at the Camp Craft Road entrance at 11:30 on a Wednesday and went down the "Hill of Life"...The trail and creek were beautiful and we saw only a few others, mostly with thier dogs, on this part of the trail.  Our idea was to try and walk all the way to the Zilker Park entrance, as we had left one car there.  Not recommended as once we got to the Gaines Creek entrance off of Mopac, the trail got hard to follow under MoPac and beyond, until we got to the 360 entrance area.  We did it but had to make our own trail in some spots and had to cross over the creek twice.  It was a nice day so we were okay with that; and we stopped to eat our lunch.  Also, we saw a sign that said "Trail Closed" but it was from the direction we had alredy come from, and no sign before that.  So, that mile and a half or so between Mopac and 360 is the most difficult. ...Remember also, that this entrance is in a neighborhood area,so there is limited parking, and you probably cannot park there on a busy weekend.