In my experience, the answer to the question is no.
The two main gripes seem to be overcrowding and old trains. Whilst I don't dispute there are places in the north where it's possible to experience heavy peak overcrowding, with exceptions I still don't think it's as bad as in the London area. Yes the 17XX out of a major city may be filled to bursting point for the first couple of stops, or maybe a little further on somewhere like the Bolton corridor, but I'd still say people are standing for much shorter distances than in the London area. "Rush hour" in the north is still roughly 1700-1800, whereas in the south east we're now talking about 1530-1930, with many trains still crowded either side of that. Same in the morning, where in the London area it's now quite easy to find full trains as early as 0600.
What I'd say is worse in the north is off-peak overcrowding, especially that associated with events. This is less of an issue in the London area as there is more stock available from the peaks to provide longer off-peak trains across the board, plus the generally longer lengths can absorb fluctuations in demand that little bit better. It's still possible to find heavily overcrowded off-peak trains in the London area at times though.
As for the age of rolling stock, I confess to getting a little tired of hearing about this. My local line in the London area still has trains dating from the mid 1970s, and until recently all the rolling stock dated from BR days. As long as stock is reliable and well maintained I really don't see the issue. I do agree however that some of Northern's rolling stock could and should be presented better.
On balance, given the constraints of financial viability, I feel the north's rail service isn't bad at all. Not perfect by any means, but not nearly as bad as some make out.
Yes there are a few ancient trains on routes around London but the point is they are not Railbuses where you may have to spend a 2 hour journey on them, and most are down for replacement in the next few years.