* He was a traitor. Glyndwr betrayed his king, Henry IV of England, and fought against him in the Glyndŵr Rising. This was considered to be a serious crime at the time, and it led to Glyndwr being declared an outlaw.
* He was unsuccessful. Glyndwr's rebellion ultimately failed, and he was forced to flee into hiding. He died in exile in 1415.
* He was a failure as a leader. Glyndŵr was unable to unite the Welsh people under his banner, and he was often betrayed by his own supporters. He was also unable to secure any significant victories against the English.
* He was a burden on the Welsh people. Glyndwr's rebellion caused widespread destruction and suffering in Wales. Many Welsh people were killed, injured, or displaced from their homes. The rebellion also led to a decline in the Welsh economy.