Definitely worth a visit. Beautiful Gothic Cathedral on par with Notre Dame in Paris. Construction of both Cathedrals was completed within a year of each other and took about 400 years to complete....No lines, easy access.

This is amazing. As far as I can judge the only church what can compete with Sagrada Familia.
You should take the time to see and enjoy this,

Walk around and check the architecture, look up to see the gargoyles. Check out the Golden Portal (Zlata Brana) and the Clock tower. When you enter, the beauty of the large stained windows is striking.
The famous St. Wenceslas Chapel is very ornate, studded with jewels, constructed over his tomb. It is always crowded with tourists trying to get a peek inside. Also unfortunately frequented by pickpockets blending into the preoccupied crowd. Speaking from the experience of a very close call.
The ornate tomb of Jan Nepomuk is made of solid shining silver - tons of it. Incredibly detailed beautiful work of art. You can't help but wonder, if it could be duplicated in modern times.
The Royal Crypt is located steps down, the remains of Bohemian Royals are buried there, Charles IV among them.
It seems that everybody visiting Prague comes here, sometimes more than once. During an early mass on Sunday the doors close. If you want to enter, be prepared to stay a while.