I did the retreat for the WDW Half.
I was running alone. I was asking my aunt and cousin (who came in from Daytona to hang out with my son all night and until I was finished) to NOT come see me finish. I am a heavy sweater and need a ton of water, I need electrolyte replacements during a longer run, and I'm finding that I *have to* eat something QUICKLY or my stomach sort of cramps up and won't accept food for hours and hours. I wanted a place to replenish myself.
Also, for TOT I missed my corral (and another two) because I got caught in a bathroom line. Everyone around me didn't care when they started, and said it's no big deal and I wouldn't miss anything. I think, now, that they were much faster runners than me that knew they could catch up, or maybe they were further back in corrals than me. I didn't want to get lost again, and figured having A place to be beforehand would be useful. In addition, I have bad night vision and felt lost even before I got into that portapotty line, and having A place would be nice to feel that I belonged.
In those ways it worked out well. I was later than I wanted to be for some reason, but I did bag check FAST and had a place to hang out in.
When they said it would be temperature controlled I believed them. That was an error. It was chilly in the morning and I wanted it to not be chilly. It didn't seem much different than outside once I was done. I wanted it to be slightly chilly then.

Basically, the control of the environment basically seemed to be lights and a roof.
When I got back I did NOT like how far away it was from the finish. I also wanted more signage, because everything looked so different in the daytime vs early early morning. I didn't really know where I was going.
In the morning, the private portapotties were good and clean and decent.
After I finished the Half, ate, managed to pull off my compression socks, and rested a bit, the portapotties were a freeforall and were gross. No soap at the sink things. No direction on the sink things so it was hard to figure out. Some man had gone out the wrong door and was in the women's area, and he didn't care at all. Well...I did. There were no changing areas that I could see, and I was pointed to the big portapotties. EW.
There wasn't enough vegetarian food, but what they had was decent and fatty and protein-filled. They had hot sauce so I could eat the always-heinous-IMO Disney scrambled egg product. They had muffins. They had COFFEE. And muffins. Oh and coffee.
It just so happened that I had come down with some awful plague a few days before the run, and I felt like utter junk. I had started to lose my senses of taste and smell (they were basically gone for weeks) and that was about the
only meal I was able to replenish myself with. (from Jan 4-18 I lost at least a pants size if not more, and DH recoiled from me when I picked him up at the airport, I looked so gaunt and scary...I can only imagine what it would have been like if I had not had all those muffin calories at the Retreat)
DH and DS will be there for my next WDW Half (I'm having a do-over; I can't let that one be my only attempt at it) so they can bring me all sorts of food and make sure I have chocolate milk and they can help me take off compression socks LOL and they will be my retreat.
But if I were running all alone again I would do it again. The Retreat helped to take care of me when I needed it. (people there didn't; but what they had there did)