At the end of the first series, it was already going downhill. When they brought it back, it was NOT good and rapidly went to hell; the writing, the acting, the PC garbage...ALL OF IT!
Oh sure, the technology was better, less "crude", but family UNFRIENDLY, and they did away with the multi-levels, the "in" stuff, which made the original SO great! What you only know is the damned dumbed down crap, served up as worthwhile.
Hell...TORCHWOOD was more multi-leveled, complex, and even with the PC crap and the homosexual stuff, was better written and acted; not to mention the fact that unlike DOCTOR WHO, was NOT meant for kids.