The bristles are really soft, which is good. The bristles are not biodegradable, as they are made of nylon-6. I do not like that the bristles are not levelled (the upper part of the head and lower part are longer than the middle) which gives the feeling that the middle part of the head doesn't really touch the teeth.
I really loved the fact it is ecological, but the bristles are very hard. unfortunately I won't buy it again because of that. but I also but the sensitive one, which I hope is a lot softer. I haven't opened it yet.
The brush part is soft and can be used with confidence even for me who has sensitive gums. The taste is tasteless. The size of the bed is just right and it is comfortable to use. If you use this, you cannot use a commercially available toothbrush.