Used to be a walk in job, people burned part of it down, got easier. Climb to the top was fun, a ladder section missing above a pool of water of questionable depth and hygiene.
Last I drove past it looked like some form of hippie commune had moved in, maybe ask them nicely if you can have a look around? There used to be ABB's warehouse there, freaking huge complex 500m down the road, but that's gone too.
I think there's actually a shop that's moved into one of the buildings on the site, kind of a hipster op shop I think.
There seems to have been a bit of a build up of equipment and bits and pieces in the outdoor areas over the last year or so.
The cut most of the ladders down ages ago, but if you're creative some places can still be climbed.
I did it back in about 2009 and it wasn't anything particularly special, some cool reasonably new switchgear scattered around though.
I lived around Newport for a while a couple of years ago, and to be honest there isn't a huge amount to explore, land is at way too much of a premium. The old Bradmill site used to be fun though.