Things to learned while setting up OBSMe coming from Debian background, and OBS coming from SuSE/RPM world, there are some quirks that can take by surprise.
Well done packagingUsually web services are a tough fit for Distros. The cascade of weird dependencies and build systems where the only practical way to build an "open source" web service is by replicating the upstream CI scripts. Not in case of OBS. Being done by distro people shows.
OBS does automatic rebuilds of reverse dependenciesAka automatic binNMUs when you update a library. This however means you need lots of build power around. OBS has it's own dependency resolver on the server that recalculate what packages need rebuilding when - workers just get a list of packages to install for build-depends. This a major divergence from Debian, where sbuild handles dependencies client side. The OBS dependency handler doesn't handle virtual packages* / alternative build-deps like Debian - you may have to add a specific "Prefer: foo-dev" into the OBS project config to solve alternative choices.
OBS server and worker do http requests in both directionsOn startup workers connect to OBS server, open a TCP port and wait requests coming OBS. Having connections both directions is a bit of hassle firewall-wise. On the bright side, no need to setup uploads via FTP here..
Signing repositories is complicatedWith Debian 9.0 making signed repositories pretty much mandatory, OBS makes signing rather complicated. obs-signd isn't included in Debian, since it depends on gnupg patch that hasn't been upstreamed. Fortunately I found a workaround. OBS signs release files with /usr/bin/sign -d /path/to/release. Where replacing the obs-signd provided sign command your own script is easy ;)
Git integration is rather bolted-on than integratedOBS provides a method to integrate with git using services. - There is no clickety UI to link to git repo, instead you make an xml file called _service with osc. There is no way to have debian/ tree in git.
The upstream community is friendlyIncluding the happiest thanks from an upstream I've seen recently.
SummaryAll in all rather satisfied with OBS. If you have a home-grown jenkins etc based solution for building DEB/RPM packages, you should definitely consider OBS. For simpler uses, no need to install OBS yourself, openSUSE public OBS will happily build Debian packages for you.
*How useful are virtual packages anymore? "foo-defaults" packages seem to be the go-to solution for most real usecases anyways.