I rode Whinlatter for the first time a week ago.
It's a pretty good trail centre, but as others have said, it seems a bit redundant to build a trail centre in the midst of (probably) the best natural riding in the UK.
It was great for a Friday afternoon warm up with limited time though – but the riding we did on Saturday (including an insanely technical descent off Cat Bells) and Sunday (Grizedale bridelways) was far more rewarding.
Might be worth getting the Vetebrae Graphics guidebook to the Lakes and trying a couple of the routes from that? I haven't read it myself but the Dales one is quite good.