why is the site login still a mess?

We had some problems last week (around the time of your posts) with our SSO server, that would have been why you experienced that problem. Sorry about that, it should be resolved now.

absolutely horrible to use this Forum yes :-)

It's horrendous.

Cannot login from iPhone and the desktop browser keeps going in a loop.

Makes me want to leave the forum altogether.

I'm lucky I've managed to get this far to type this!!!

Same here. It’s the worst/most frustrating forum I’ve ever used.  The default view should be latest activity too - posts from a few days ago with a new comment are listed in the order that they were first posted instead of by latest post.  The login thing does my head in.  Takes about 10 attempts to stop the loop.

What I realised meanwhile is that when I am opening the PioneerDJ Website I am in the 'US Location' of the site while I am located in Germany. When logging on to my account it works but I got Problems with the Forum. 
Changing to the 'German' Location first and do the Login afterwards, allows me to log in for the Forum as well.
Not sure if this was just by Chance but it worked for me.

yes it is terrible, in my case it almost always goes into a loop, and i can login only clearing up the cache of the browser

most of the times i don't post or comment just because i don't feel like going through the login hassle

Yes, such a PAIN to log in these days. Maybe it keeps keeps the number of complaints down! haha