I got Mediocre working together with WinBoard and played a few games. A few observations so far:
1-3 plies; Instant moves.
4 plies; 2-3 seconds.
5 plies; 20-25 seconds.
Since we have no move ordering what so ever and no optimizations like transposition table etc. we can not expect the engine to be much faster. I think this is quite acceptable at this point.
Playing strength: It plays some ridiculous moves. Moving pieces back and forth, having no plan at all. But as soon as a combination of some kind comes within its search depth it finds it without problem.
One severe problem is the horizon effect. If the line ends with its queen capturing a pawn, the engine can play for it without realizing the queen can be captured the next move, since that is out of his 'horizon'.
This will be solved effectively with quiescent search which I will add as soon as I get a few bugs worked out.
Bugs: I have run into one bug so far when playing, the engine tried to move his king into an attacked square. I will check into what the problem was. The more games played the more bugs will be revealed and hopefully I can work them all out.
What now: I will make sure everything works smoothly, and get the engine vs. engine working. After that it is time for quiescent search.