I just came back from a mostly solo trip earlier this month (was solo most of the time but met up with a friend from here a few times).
Had lots and lots of fun. I got to do things on my own schedule - so did a couple of insane long days (7am-2am, 8am-3am), slept in on other days, did stuff when I wanted to, had meals only when I got hungry, etc. I also had a few random conversations with people in line, and with CMs (who were all incredibly nice and happy to spend time just chatting about really random things).
Oh and I found it fairly easy to get FP+s and ADRs for a single person. I only did my FP+s and ADRs somewhere around the 30-40 day mark, and got FP+s for Anna+Elsa, Wishes, 7DMT, and got ADRs for Be Our Guest (dinner, and then breakfast when it was announced) and pre-park opening Crystal Palace. (I didn't do all of these in the end though!)
I'm single though and this was not the first time I've been to a Disney park on my own (started with DL as was in California for a conference and had no one to go with me, and the amazing time I had there meant that I was no longer worried about doing Disney on my own... since then I've also had a few solo trips to DLP). I've also been taking flights alone since I was 18 so am fairly confident travelling on my own in general.
Safety is another aspect - I stayed on-site and never once felt unsafe while I was on WDW property. Even when it was really, really late at night!