It's a beautiful cathedral! It's a fine example of Baroque architecture inside and outside. The…read morevaulted and arched ceilings are all encased with beautifully detailed frescoes featuring St. Gallus along with Biblical figures and cherubs. The color scheme of the ceiling and trim (aqua, coral, and gold) really highlights these paintings. The contrast with the white columns makes it look like a colorful tiered topping on a wedding cake. It may not be as ornate as the cathedrals in Italy, but it's most certainly elegant in style.
The one common thing that I did notice in the cathedrals of Switzerland is that there is still a separation between the sacred part of the church (or chancel) and the rest of sanctuary. It's nice that they've kept that tradition, but it doesn't allow visitors to truly see everything. I would have loved to see the Bell of St. Gallen, but that whole area is gated by the tall screen. Maybe it's to protect all of these religious symbols. Can you tell that I'm not Catholic?
The facade of the cathedral is just as beautiful with the clock towers and statues. It's the main focal point in St. Gallen as it should be. The city around it is very charming as well. Make sure you take a walk around the grounds and city while you're there. There's all kinds of medieval architecture to discover while you're there. Very enjoyable!