ah, I used to work in Droylsden so used to go to Clayton Vale regularly when it first opened. It's ok, for a city centre-ish trail centre, but when it first opened there was broken glass all over the place and dog walkers swearing at you for being on the marked mtb route, etc. so I hope it's now better... (or is that like trying to take the Manc out of the place?!?) It's good for a 30min blast, as it's better than nothing, but it feels like they tried to cram in as much as possible (to advertise the 11miles of tracks, or whatever it is), so there's little long downhill/flowing sections. In some respects, I think a little less would have been more, if you get me.
1st time you goto a "proper" trail centre like Llandegla or even Leeds bike park, it will be a revelation. After a change of job and moving to the edge of the Peak District I seem to have plenty of my doorstep here. If you're east Manchester, then it's well worth a drive outside the m60 to the hills...