I was diagnosed with Asperger's (now HFA), with a possible co-morbidity of ADHD (inattentive type) about 10 years ago, at the age of 31.
I was lucky enough to have a GP who took me seriously and I was referred through adult services, although this probably wouldn't be the case now.
I am HF and hold down a relationship, senior career, friendships and so on, so in terms of 'what has brought me?', probably nothing more than a heightened sense of self-awareness, and some self-forgiveness. I don't, for example, really require any special accommodations at work.
Interestingly, my mother, who was initially very, VERY averse to the whole process, has gained enormously - probably more so than me - from my diagnosis, and has also achieved a level of self-forgiveness (my sibling is NT and I was brought up in late 80s/early 90s Scotland, where autism barely existed, and certainly not in girls).
The process is long and tenuous and can be quite emotionally painful, so I'd say go for it if you want to, but be prepared.