They have to be "likeable" and "thoroughly" tested.
I'm not sure what you mean by "likeable". So far, everyone who has played them has thoroughly enjoyed them. As for the extent of testing, I've been doing extensive single player testing, and some Multiplayer testing. The bugs we've turned up have been pretty minor. In PvP, there were no bugs at all, in the two tests we've done of it so far. The only real difference in PvP between an Evil Dave mission and the old missions is the size of the map and how long it takes to find the bad guy. Deep scanning is a must.
It might be worth getting with Die Hard, Q, Starfleet Command HQ, and a few others to get other views.