I think they're great, just be careful with lose threads and other possible things they could get tangled in. I recommend checking it once a day or so as there have been a few gruesome stories revolving birds and happy huts. They are really great things thought to have. With that being said they're not good for all birds; female birds you have more of a risk that they will feel too comfy and possibly lay an egg. Although that mostly occurs with cockatiels and love birds and other birds that have a bit of a reputation for being chronic egg layers. For an african grey i think you would be fine. I have a senegal parrot, which are very close in personality with african greys, and he adores it throughout the Canadian winters. In the summer and warmer nights, not so popular. If your bird enjoys it though by all means keep it in for him.
