I only took A-level Sociology because A-level Psychology clashed with my other choices, but it ended up being my favourite A-level and now I'm applying to study it at university.
I found it really interesting as it gave me the opportunity to tie in my own experiences of being in a family and being involved with the education system to either empathise or disagree with theories about their functions. In a nutshell, there was a lot of 'questioning the system' (especially in the education module) and that gave me a certain sense of empowerment.
But as mentioned above, there is a lot of content to cover and learn, such as: statistics, sociologists' theories and their dates, basic concepts etc. but if it that is what you're interested in and believe you can do well, I see no reason why you shouldn't continue with it. On the flipside, if you're not interested in it then I would strongly advise not taking it; you wouldn't be motivated to learn the vast amount of content involved.
There is also a lot of essay-writing and evaluation involved, which will work in your favour if you think you want to study a degree that itself involves a lot of essay-writing.
I've never heard of Sociology being universally 'undesirable', technically any subject can be 'undesirable' if you've taken subjects that are irrelevant to your chosen university course. Yes, Sociology will be undesirable if you want to study Maths at university, but Maths would also be undesirable if you want to study Sociology at university. In my opinion, it works both ways.