I would say most travellers avoid Guatemala City. Instead they opt to stay in Antigua which is very calm and relaxing. The problem is the roads are terrible. If they are not being resurfaced then there are accidents, motorists driving the wrong way (motorcycles do this all the time) or collisions with animals. This can make travel between Antigua and Guatemala City airport problematic.
So, the last night before I flew to Belize, I opted to stay in the city. Although there is a lot of crime and poverty here I still managed to survive and I still have both my kidneys 🙂
I think the most important thing to remember is that most Guatemalan people are friendly, helpful, and outgoing. They don’t want to rob you or take advantage of you. Still, you should exercise a high degree of caution, especially at night.
Lots of little hostels, hotels, and B&Bs have started to pop up close to the airport for obvious reasons. To get to most of these you need to enter a gated community. This makes it quite safe, but can be a bit off putting seeing guys with guns and large barriers to get in.
The bigger western hotels in Zone 10 and Zona Viva are on city streets. They will have armed guards when entering and leaving. You should have some id handy if asked. Unfortunately, in case of issues the police are unlikely to be a big help. They are under paid and take a lot of bribes.
Now, saying this, the city also has some fantastic places to eat and they are cheap compared to Western standards. To get around I used uber. It was affordable, fast, and safe. Most drivers didn’t speak English, but it presented only minimal issues.
So my tips – absolutely do not walk at night. Not even a short distance. Take an Uber or taxi. Carry only enough cash that you will need for that day. If you are walking short distances in the day time (which I did without concern) don’t dress in fancy clothes or wear a nice watch. Try to blend in with the locals. Don’t make yourself a target.
Overall most visits to Guatemala City will be trouble free, but I would suggest you use caution here.