The on-board Wi-fi is the only difference I’m aware of (though I’m happy to be corrected, if anybody knows better) apart from the different case colour.
I didn’t want the Apple-esque white case but I was half-tempted by the on-board Wi-fi.
However, the clincher for me was the 1000S being available at a reduced price from Humax Direct (£195 inc. delivery) whereas the 1010S wasn’t and hence would have cost me at least £250 new elsewhere.
The combination of preferred case colour and big cost saving was a no brainer for me. 
Edit: Humax Direct ‘Grade A’ page…
http://www.humaxdirect.co.uk/prodCat.asp?cat=factory&type=sat