We did something similar at the end of the garden with emphasis on native wild species and minimal maintenance - aiming for more wild than garden. The low maintenance didn't quite work as planned. Nature helped and now we've gained brambles (probably the highest maintenance part, as if left alone we'd have no garden, and once in they're damned hard to get rid of), thistle, inevitable dandelions and a few unidentified things have moved in too. The blackberry, nettles and dandelions need regular encouragement not to do too well. Less effort than a boring lawn though.

First year was fairly underwhelming, since then have had all sorts of insects and birds as constant backdrop. Last few years two pairs of birds, not sure if same pairs, have used it for their nesting spot - there's always one nest in the blackberries. I guess brambles are staying! The back of the garage seems to have a couple of masonry bees every summer, and there's a lovely extra sound background from it all. There's constant birdsong at the back. A local cat keeps trying for those nests, but hasn't got to them yet, and has failed noisily a few times... :)

We've twice spotted a frog, but we have no pond and there's no open water near us, so that's been a bit surprising.