My co-founder, @navied and I were in the first batch with our startup, Dovetale. In a nutshell I'd say it's less "accelerator" and "incubator" and more studio with partners as part time employees helping you build. It's a very unique experience. I wrote a piece here that might be helpful.
https://medium.com/@mikeschmidt/my-expa-labs-experience-447f...
We spent time with Garret + the other partners very often. Each partner has different interests and is valuable in different ways. Since you work out of the same space you see them all the time. Working at Expa HQ definitely has other advantages but this is high on my list :)