I bought (shared ownership, so sort-of bought) a ground floor flat. It was the only one left in the building, but also the smallest.
It's OK actually. No noise from upstairs, and at least you only have one direction of neighbours to worry about. Easy to nip to the bins. Easy to let visitors in and out as the gate is right there. Easy to go to the shops right across the street, in a few seconds flat, and back again. No stairs or lifts! Easy to move furniture in, and easy to carry shopping and stuff home.
You do hear the gate slamming, but I very quickly learned to tune it out.
Downside - not being able to open the windows at night. It gets extremely hot, but one window faces onto a road with lots of pedestrians, and the other onto a communal garden, so wouldn't be safe to keep them open. Not that I'd really want to because of bugs, but I could have had a screen or something if I'd been upstairs. I'm even worried about getting a portable air conditioner, because I don't know how I'd vent it out the window, without it compromising security, so even that couldn't be on at night.
Traffic noise and pedestrians. It can be disconcerting to have loud and drunk pedestrians right on the other side of the windows (big glass windows rather than walls) at night, even though I know they can't get in. Delivery lorries for the shops nearby can be very noisy. I don't know how much difference being upstairs would make for this.
Visibility. My job working from home is actually better to be in view of the street, so that works well for me. I would like to get something a little more private though, some kind of nets or blinds I guess, for the times when I'm not working. It is quite nice to people watch, being able to see everything! I don't like that I can never open the bedroom curtains, even though I'm hardly ever in there anyway. But it would feel weird having people on the street see in to my bedroom, even in the day, somehow. I don't know quite why. Maybe some kind of nets would help in there too.
Overall, it works for me, partly because of the work issue, and combined with the visitors (also work related), and not having to climb stairs/use the lift all the time. The visibility is tolerable. The heat in the summer is awful. But having the windows open only helps a small bit anyway.