We loved CDMX
Hotel Marbella was a good value for the price and if you go without specific expectations. If you need basic accommodations that are decently sized to American expectations this place could work for you. This isn't an especially cute corner of the city, but it seems reasonable if you use a little common sense. In large part, I chose the hotel for it's proximity to the Metro, however Ubers are so inexpensive, we took those nearly every place we couldn't walk. Nearly every place we went was less than $5 USD and most of those were under $3, including La Condesa, Zocalo, and Frida Kahlo house. It also looked like there were other streetcar/bus lines just outside as well.
The lobby is very nice and check-in was easy. Rooms seemed very clean and I didn't really notice any other guest noise, maybe once or twice while in the bathroom. There is a bit of street noise, so if you are used to dead quiet, it could be a problem. But if you're a city-dweller and are used to some signs of life outside, you'll probably be fine.
Staff was very responsive whenever we needed something. My husband uses a CPAP machine and the outlet in the room was too far from the bed so the hotel engineer rigged something up so we had a makeshift extension cord. So if you need a CPAP, see if you can fit an extension cord in your luggage. Also we found an additional outlet in the (non-functional) safe in the closet that's a good place to charge your devices.
If your room faces Frontera, close the curtains at night or you're going to have some hot sun smacking you in the face in the morning.
They didn't provide washcloths, they might have them on request, we didn't ask and made do without.
If you walk to the northwest of the hotel you can find some cute local spots. We had breakfast at Volver, a hip little breakfast joint that was delicious. There is a small Mezcal bar if you want to try some different types, La Botica. El Beso Huasteca is a cozy dinner spot with friendly staff. If you walk all the way down Frontera to Av. Alvar Obregon, there are many cute/hip bars and restaurants. To the east is Doctores, which is generally not a recommended neighborhood for tourists. However I didn't particularly feel unsafe near the hotel coming and going.
Breakfast at the hotel is fine, we ate there twice for speed/convenience before starting our days. The buffet is heavily Mexican dishes but they have another breakfast that includes eggs, toast and fruit if you want something standard. We also had a couple quick drinks at the hotel bar a few nights, the bartender who was there was very nice and attentive.
This place isn't hip and happening, but if you want to see some of the real parts of CDMX and public transportation is important to you, it's probably a good fit.