Bambooi is a wonderful UK based startup, but unfortunately in their 'cheap bamboo toothbrush' department, they didn't get it right.
In general, I just don't like the bamboo part in bamboo toothbrushes, doesn't matter what kind of brand. The tip feels to big inside my mouth (I know, that's what she said).
There are so many brands out there and I tried five so far. I don't like sticking 'wood' into my mouth (again, that's what she said). The only difference I've noticed are the bristles. Some have different colours, but I can't say I've noticed charcoal bristles actually helping me. Some brushes have even thicker bristles than other (for example, the bam&boo are HUGE and seriously twice as long as the electric brush bristles, they're really not great and hurt my gums).
But hey, back to Bambooi. I don't know what it is, but after 4 weeks, with cleaning the brushes every week in vinegar, they got all slimy in between the bristles and I couldn't clean the slime out. I didn't do anything else than I usually do with my other bamboo brushes as well, which never have slime in them. So I've had to throw them away waaay too early, as I usually use a brush a bit longer than 3 months.
So unfortunately, even though these brushes only cost £1 when on sale, I won't be buying them again.