I went to the one in London last year and am going to the one this year!
So effectively once you check in, you'll be able to have an explore of a few different kiosks. There's some from third parties that will try to sell you the apps they've made and some Salesforce ones. I remember this was just before they pushed out things like Sales/Marketing/Analytics cloud etc...
You could, as we sometimes do ask what they're doing and if the idea is good, replicate it yourself making it a bit more bespoke.
There's also several forums with topics specified times. There are indeed ones for developers and administrators. You'll get an information pack with a schedule. Some things you'll be interested in, other you maybe won't be.
Is this event helpful for Developers?
You won't be sat in a classroom being educated on how to build a super-duper-Apex-Visualforce-Lightning-Fully-Tested-With-100%-Coverage-App with all the bells and whistles. But some of the dialogue I found extremely helpful. Last year I found the talk on best practices really useful! Stuck out for me anyway.
Can we learn anything from the technical perspective?
Yes! Again as I said you won't be sat in a classroom, but some of the discussions are really helpful and useful. My advise would be to look at the schedule and pick and choose.
One great thing about it is networking too. You'll get the chance to talk to other Devs and Admins and share some frustrations, knowledge and information.
The whole information that I could get by searching online about this is more kind of Sales event talking about the different Salesforce Products
You're kind of on to something. Salesforce will talk about upcoming things, new products and releases and you'll find different vendors there too.
Personally, I think it's worth going to the World Tour Events!
It's one day of the year away from the screen where you can share a few ideas and get up to speed on some of the new stuff Salesforce is doing. It certainly won't hurt attending the event.