I just got back from my first solo trip! I went 10 days, and it wasn't long enough.
Here's some things I learned -
I was comfortable eating alone, including at the character meals. The only meals I would even think about reconsidering doing solo would be buffets, and that is only because every time I got up to go get more food, I had to take my purse and everything with me, and that got annoying. With that being said, Boma is a must do for me, and I also love Crystal Palace.
I felt completely safe. I didn't go to Pleasure Island at all, though that was because I was to tired at night, and I was going to go, just never got around to it. I did go to DTD twice, but that was during the day, for shopping. I wouldn't worry about leaving the parks before dark - then you'd be misisng Fantasmic, Illuminations, and Wishes.
I completely rellied on Disney transportation, which was efficent.
Also, don't be afraid to talk to strangers. I had some great conversations with people at restaurants, people in line, and such. Also, cast members are fun to talk to to.
If you like meeting the characters, go for it. I didn't have any problems getting my picture taken with them.
Then, of course, there's the great benefit of being able to go, and do what you want. I would definatly suggest getting the park hopper pass, as there were many days I would go to MGM and Epcot, or Epcot and MK.
I'm sure there's more, please feel free to ask me anything.