it is every single aspect of presentation, tuning special stages, stage select etc are just awesome to look at and they work well.

I can't get on at all currently.  I think I read somewhere for some reason they had the game regularly checking with servers whether online or not.  Not sure if confirmed but I've seen some rumours on the forums a patch is coming this weekend which stops the game constantly pinging servers which is expected to ease a lot of the issues.

I just don't get why they seem to have expected relatively low online demand early on - surely they knew that a) the game would sell well initially and that b) a fair percentage of owners would want to try some online play early on

I was personally in huge anticipation of GT5... and there are a few things about it that are a wee bit of a let-down, but thats not where the problems with the reviews lie.

They were expected serene gold and received regular gold.... and thought it wasn't good enough. If that game had NO hype what-so-ever, it would've scored much better in the reviews than it did. The huge hype and extended suspense it was caused reviews to crash. The game didn't deliver a perfect euphoria, but what it did deliver was a racing game better than than almost anything else out there. Does it deserve a perfect 10? No. Does it deserve an 86 out of 100? No. I'd give it a 93 at the current state of the game. 

If you read most of the reviews in-depth, they bash about how it didn't do this or didn't do that, even if what it DOES DO is better than the competition, and they gives it poor scores for that.

It has a lower meta than games that are FAR worse, which means that it isn't getting justice.