1. He was quite smug about how he helped grab lots of buildings from the SSPX (back when they were good)
2. He is quite self-serving with his original creation, the "non Una cuм" position. Before he came along, virtually ALL sedevacantists were comfortable attending a Tridentine Mass of a non-sedevacantist priest (independent, SSPX, etc.) Fr. Cekada elevated sedevacantism to a dogma, saying that if you can't find a sedevacantist priest, you must stay home alone. This is seriously evil, and has done countless harm to traditional Catholic souls.
What started out as a way to eliminate the competition there in Cincinnati, OH, has spread as a cancer of Home-Aloneism throughout the United States. When a middle aged woman in Texas reads his articles or watches his videos and is won over to his position, she can't exactly go to Fr. Cekada's Mass in Ohio. So she ends up becoming a home aloner. See the problem?
In other words, Fr. Cekada is probably in the "top 5 priests" in the list of Traditional Figures Who Have Created Accretions or Complexity (read: chaos and division!) In The Traditional Movement.
3. Fr. Cekada severely disappoints me in the category of humility vs. pride. Let's put it this way: If I know 25 priests, then I know 24 priests more humble than Fr. Cekada.