Call me greedy, but I want a little bit of everything.
On the hardware front, I’d like to see more add-on boards/sensors. For home-automation projects, maybe some Z-wave stuff. For car projects, maybe an OBD2/CAN interface. And of course, libraries to support them.
And as for resources, we could always use more/better code examples and instructions, especially for some of the more non-standard tasks (setting up local development toolchain, local server, etc).
That said, I think the Particle team is doing a great job!