Really "quite awesome" once stepped inside this cathedral was seeing its main aisle which I would just describe as one "packed with grandness" where along its both sides are not small but "quite sizeable" paintings depicting the life events of Christ (and with brief descriptions of the artists below from which can be determined the "historic ages" of the paintings themselves!) and also a "unique sight" (as such had been seen in no other cathedral before) which is that of "super-sized" medals likely kind of bigger versions of the medals awarded in this country for exceptional services & such. So yes, a big cathedral with quite plentiful to see inside where apart from those along the main aisle are also shrines & secondary altars (along the two length-side aisles) also with their own displays of interesting sculptures & such, this cathedral actually is one reminiscent for me of those in South America (with grand & ornate interiors in many of the "main cathedrals" of the cities) than in Central America (with just generally plain cathedral interiors from Panama & up with a few exceptions such as the Cathedral of Leon in Nicaragua & the Metropolitan Cathedral of Mexico City).
And with the entrance from a "pedestrian street" located on the south side, very conveniently right beside that entrance is Mercado Central (a great place for all kinds of Guatemala souvenirs & also like a food court down below for some delicious "local meals"). And yes, also definitely to stop by while at this area are the 2 sites at just a very short walk from this cathedral (to the right after coming out): the city's "main plaza" Plaza Mayor de la Constitucion (with really quite a bit of space to walk around where at about its center are a big national flag & a fountain and yes where the "west face" of this cathedral is on the Plaza's east side) and the "long building" of Palacio Nacional de la Cultura on the Plaza's north side (with 2 levels of a "fairly impressive" interior to see on an hourly-or-so "guided tour").