Well Brotherhood is more than twice the size of Fate/Zero so there's bound to be more piff moments, but I maintain that pound for pound Fate/Zero is every bit as good.
It has intricate and complex characters, awesome fights, great animation. The pacing is also really good, there's not a wasted moment. It's also somewhat darker and thematically more complex than Brotherhood. Brotherhood had quite a bit of comic relief, in Fate/Zero only two characters provide comic relief.
All that being said, I highly recommend it. If you do pick it up, keep an eye out for the homie Rider.
It has intricate and complex characters, awesome fights, great animation. The pacing is also really good, there's not a wasted moment. It's also somewhat darker and thematically more complex than Brotherhood. Brotherhood had quite a bit of comic relief, in Fate/Zero only two characters provide comic relief.
All that being said, I highly recommend it. If you do pick it up, keep an eye out for the homie Rider.