We arrived around 10am at the South gate of the Zion NP and drove all the way along the scenic drive to the beginning of the the Riverside Walk. The plan was to get a first impression of the park and then to stop at the small side tracks on the the drive back. The drive was surprisingly short and took about 20 minutes. The Riverside Walk itself is a very easy and short path along the river up to the Narrows, in which you have to wade a bit to get to the part where it is just a few meters wide. Here is a picture from the walk:
My first impression of Zion was that it is quite similar to Yosemite and its valley, but way smaller (and dryer)- both have the beautiful and steep yellow-orange cliffs with white mountain tops. One of the best parts of the day was the short ascent to the Weeping Rock. It did not look very spectacular from down below, but when you enter long cave, you will see the mountain panorama through a curtain of water drops.
Finally, we went up to the Emerald Pools. The pools are not that incredible but the views along the path are awesome. Here is picture from half-way up to the first pool.