I have lived here for a year and a half, and I love it. Everyone in the leasing office is incredibly helpful, courteous, and kind. I love that they keep dog treats in the office, and make my dog feel welcome too (you should like dogs if you live here - most people have one).
The location couldn't be more perfect - right next to union station, the 16th street mall / LoDo, and LoHi. Neighbors are friendly and quiet for the most part. I do hear noise from the train because my apartment is right above the tracks, but I stopped noticing it after my first week of living here, and there are tons of units that are not above the tracks (my cousin lives in one away from the tracks, and NEVER hears the train). I almost never hear noise from neighbors.
The only downside that I see is that historically it has taken longer than I'd like for things to get fixed when broken. But there is new management in-house now, and I think they are working really hard to improve that. There are a lot of renovations going on right now that really look like they'll be terrific, and I really appreciate that management is being 100% transparent in sharing a very detailed timeline for each renovation. That is a fantastic system, and I'm really excited about it.
Overall, I absolutely would recommend living here (and I have, actually - three of my former coworkers live in this complex because I recommended it to them - they have been happy with it as well).