Custom professional-made objects, textures, models, everything! Just awesome;
Amazing music(especially tank music is epic);
Unique panic events;
Not linear levels, multiple paths and even events everytime are different;
Finale area is huge and very well detailed.
I had some lags with music(sometimes need to restart level to turn lagging music off);
Long way to rooftop and if you died you need to go through like 4 huge floors all over again;