Uuuuuummm well, for year 10 my parents didn't want me going alone so they organised a family friend for me to take. I hadn't seen him since we were both 5 years old but fortunately he turned out to be really nice! Except he danced a bit weirdly...and there was some awkwardness because in the space of an hour I had to learn everything and teach him everything that had happened to us in the past...ten years?
I didn't go to the year 11 semi-formal (parents wouldn't allow me) but for year 12 I'll probably take a good friend. Hopefully I'll be 18 by the time so my parents won't try and arrange another partner! I'd like to have some say in the matter this time.
I guess it's your choice, but I'm against taking random people - if I had a choice I would NOT take that guy again, not that I have anything against him, but it was so very scary.
edit: I just forgot to answer the question! I think going solo is okay - it means you don't have any "responsibilities" like organising their transport etc - but if you want to dance the night away with someone then it's probably good to take a friend as opposed to having to snitch another person's (they might take it badly, like what happened at my year 10 formal with a good friend of mine)
And it's not everyone's cup of tea but in the very very unlikely event I get a boyfriend in time for my year 12 formal (in December **sigh**) I probably wouldn't take him anyway, just because I would much rather spend the night with one of my best friends, and because I'd be scared we'd break up in an ugly fashion and then I might be tempted to destroy all the photographs of the two of us...but who knows? Maybe things will change after the HSC...