The most difficult part was to register for the race, as the website went down a couple of times when they started the selling bibs (bib-only). I decided to register for the half in August and it wasn't sold out (race is in September). You need a medical certificate just like in Italy, I used my Italian certificate for athletics in competition and provided a translated copy (italian to french).
I went to the expo as soon as I got off the plane and it was super easy to get around and pick-up all the things you need for the race. There's an information counter where you can ask help if needed.
Corrals were big. Too many people, but it worked-out well as they were releasing people in small waves as the streets are not big enough for everyone. If you want to run fast, it was almost impossible to do so as everyone is there for the experience and not the time. I think cut-off time for the first corral was around 1h30.
I only did 1 stop for character pictures and the line was moving fast. Water stops were amazing, you could find water, gatorade and different things to eat. It was my very first half so I didn't know I was going to be so hungry at km 15, I really appreciated the snacks!
The finish line was a bit crowded but considering the amount of people running everything was very well organized.

Let me start by saying this was my first major and my first marathon so nothing would beat the feeling of accomplishment I had finishing it.
We went to the expo by metro, it was easy to walk there following the runners. Expo was huge but bib pick up was easy and really fast. However, the lines to pick up preordered items were terrible and unorganized, I think I was there at least for an hour waiting and it made me want to go away right after I picked up my stuff. I went to the shop near the zoo which was ok to buy race merch the day after the race.
We stayed near the start and walked there, we got to see the Elites starting and stopped at the port-a-loos on our way to our corral (first marathon so last corral). No lines as we selected poncho instead of bag drop-off.
The race itself was good, I'm not sure if the "traffic" was because I started in the last corral but the streets were pretty crowded, if you're trying to follow your pace it can be difficult. Water stops were only on the right side of the street and it would have been appreciated to have them in both sides with paper cups instead of the plastic cups they use. They only have 1 stop with gels towards the end, but I was carrying my own so that wasn't an issue.
The course is easy and flat, and in 2018 I saw people with signs saying world record 2h01 39 so it was exciting to be running in that atmosphere. I had read so many times that you should save your energy and not sprint when you see the Brandenburger Tor but that's impossible even if you know you still have a few hundred mt to go. I finished the race with so much energy from people that I could've kept going!
Make sure you pick up your beer at the finish line, for the rest... just follow the people and you will find everything you need.

The overall experiece was great, we didn't expect the heat so it was hard to run 15 km in the sun, after that there were trees and houses so you could run at least a bit in the shade.
The race starts at 10 am, a bit late specially for the weather conditions this year. We took the bus they offer from the train station to go to Abano, not the best but it works good. Luggage deposit was easy to find and fast to retrieve your bag after the race.
For the aid stations, many options as it was the second half of the marathon course (tea, salts, water, fruit). The course is pretty flat, I remember only two overpasses. People in Abano (where the spa hotels are!) were cheering in their bathrobes so that was fun, I didn't expect many people cheering but it was quite good considering the amount of people running both marathon and half (about 3500 I believe). The course scenery gets better once you get into the city, as you see the typical constructions, Duomo, Sant'Antonio Church, and the finish line is at Prato della Valle, one of the largest squares in Europe.
This year the sponsor was Nike and I loved the half-marathon t-shirts (white with the red logo on the back). The expo didn't have many stands and I hope they can improve that in the future.

Expo is 10 minutes away from the metro station, you can easily walk from there. Bib pick-up was quick and easy. Being the most important half marathon in Italy, I expected the expo to have more things to offer, but it wasn't bad. Small detail: race t-shirts were too small.
You can take the metro to the start line, everything was running smoothly the morning of the race. There are trucks to leave your bags, taking them to the finish line. The only thing I think could be improved is the availability of portable toilets before the race, I spent at least 25 minutes waiting and it was full of people doing their thing on the trees.
Start was good, not too crowded as I had imagined so the waves worked-out well. Race course is linear but with hills, be prepared for that. Not many people cheering in the streets but if you know Rome, it's nice to see the street (Cristoforo Colombo) empty, something that doesn't happen often. Water stations every 5 km as in any Italian run, with water in the first one, water and salts in the second one, water and orange slices in the third. At the finish line, there were many things to eat/drink (you could get a gelato this year) and a massage tent. They give you a kind of poncho to cover from the wind since you are on the seaside.
To go back to Rome, there's the train less than 5 minutes away from the finish line. It was crowded but, for Rome standards, surprisingly very well organized. Remember to buy your ticket in advance and you can avoid the long lines in the ticket machine.
Can't wait to do it again next year!

Expo is small but there were no lines for bib pick-up, don’t forget to print your confirmation letter. T-shirts run small so if you do this half marathon, check the size before picking up the shirt (they have like a counter with all sizes to try them on).
I was staying not so far away from the start so we jogged from there to warm up. I couldn't believe that there were no lines for the toilets at the Stadium, it was great! A bit crowded at the beginning, not too many corrals and the release was in only one wave.
Water stops every 5 km, some fruit and salts. Elevation is not difficult as you have only some bridges but the rest is pretty flat. Some streets are narrow and the change of pavement might be tricky in the rain, I didn't have any issue though.
In the course, you see: Stadium, Porta Nuova, some churches and bridges, the Castle, and other historic landmarks. In the past you could you inside the Arena right before the finish line, this year there was something going on inside so we went around the Arena.
We didn't check a bag so I can't tell my experience about that part, we also missed the pasta party after the race.
There was a 5k and the Duo Half Marathon, where you can do the half in two, switching places mid-race.