In general, I liked it, but it always irked me that its Ruby underpinnings made it hard to upgrade/migrate stuff (we basically just swapped LXC containers at one point, not sure how it was handled during the last upgrade). If anyone ever manages to do a credible alternative that does _not_ use Ruby in any way but keeps the overall GitHub-like workflow, a lot of operations folks will switch _instantly_.
(Like https://try.gogs.io/explore, for instance)
Also, like some commenters already pointed out, the CE edition was ridiculously limited in some regards - we mostly skipped the bits we didn't like and did product-level ticketing outside it (using Trac), with Gitlab issues used only for "techie" stuff, tracking fixes, etc.
But today I'd probably just sign us all up for GitHub and be done with it, or fire up a VM image from some marketplace - there's hardly any point in maintaining our own infrastructure or doing a lot of customization.