I like the engine, and working with it thus far has been a very enlightening experience for me, but there are things that are broken in the manual, and the newbie’s guide is several versions out of date, and so on.
If there were a cleaner, more easily accessible system for developers to maintain, modify, and develop the code, that would be a big hook. Updating the gallery, creating a few small engine demos (not tutorials, but maybe something like irrlicht’s demo has), and maybe implementing a browser-based IRC widget would help as well.
The engine is there, and the seeds of a strong community are in place. What’s needed now is the hook, stability, and major convenience that sites like Blender3D, Crystal Space, and Ogre maintain. Put those tools in place and decide on a method to structure development process (e.g. who gets to go through all the suggestions and changes to code and decide what goes and stays.) Once that’s done, start aggressively advertising, maybe putting out some machinima on youtube, do the whole viral marketing thing, and heavily abuse the Disney advantage until you get a couple dozen core engine dev / volunteers.
Those volunteer developers are basically all that significantly separates Panda from the big players (CS, OGRE, Blender) . And it would be awesome to see 2-3000 active members posting daily, even if they’re 90% “I r new to teh gaming seen, kan u help me LOL !” and whatnot. Python might make alot of those games possible, where c++ can just as easily crush a newbie programmer/game designer.
Anyway, just rambling. Definitely not complaining, because the site and Panda engine are great, but they could be more, and if shooting out ideas might help, then at least I’ll try 
