I actually created an account here to ask the exact same question...
I'm 37 years old and have been diagnosed earlier this year (8 months ago).
I'm not gonna go through the process that made me seek a diagnosis here, but it was a massive relief as well as a shock.
Not knowing much about Aspergers and autism until that point, I had no idea that there was a connection between sensory hypersensitivity, being blunt, being better off on my own, not recognising emotions, not understanding social cues, repetitive behaviour, restricted interest, etc.
Everything that I'd been through suddenly made sense, and I could stop blaming myself for being less capable than most people in social situations. I understood why I have to block my ears when an ambulance or police vehicle drives past me, while other people look completely indifferent to these horribly loud sirens. And so much more.
On the other hand, all my difficulties seem more obvious to me now. For example, how bad it makes me feel to be in a crowded supermarket (harsh lights, loads of people, too many sounds), and finding out they've discontinued the stuff I get all the time (intense frustration). It feels like it's worse than before but maybe it's just that I'm more aware of it.
Very often I suddenly remember an incident from the past, that I hadn't thought about for years and years, and see it in a different light.
It's like the twist at the end of "Shutter Island". Once you know what's going on, you can watch the film again and it all makes sense (maybe not the best example in terms of mental health, but a good example in terms of storytelling).
Finally I was hoping I'd be able to get out of this invisible cage one day, but now I know I have to live with it. It's not gonna go away. Fighting it for 37 years probably helped me push the bars apart a little bit but it's been so hard that it almost killed me.
So yeah... I say it's a giant leap on the road to inner peace (though I'll certainly never get there). The day of the Aspergers assessment I also discovered I had ADHD. I had no idea what ADHD was so that was another shock.
Sorry for super long post. 