I had a lot of hopes for Github Issues [0] but since they announced the product on last year's Universe event, there were not many news. Maybe this November they will come back with an update.
At this point, I feel Jira is like WordPress. It maybe slow and overbloated, but you can have absolutely any plugin and/or integration you can think of.
> Project planning for developers
> Create issues, break them into tasks, track relationships, add custom fields, and have conversations. Visualize large projects as spreadsheets or boards, and automate everything with code.
But from a project management perspective it does lack in some perspectives. This mostly depends on what you need and how you use it. Unlike Jira, Github issues does not come with plugin support and can't be customised as much. This makes it easier to work with for developers but might not give you all the power you might want while planning the project. For example, to my knowledge, theres no way of assigning "Story points" and having "burn down charts" in Github issues; as its not a tool ment for doing Scrum. But if you're not doing Scrum then it doesn't matter. It also doesn't have a concept of sprints and epics. But I does have both tags and releases which you can use for planning.
And the new Github Issues beta looks to add a lot of features: https://github.com/features/issues
Scroll down to "break issues into actionable tasks", and they have an example that's even labeled as an "Epic". They are definitely headed in the same direction as Gitlab.