There are still a few problems with using the various "Mumsnet Classic" options. However, for a lot of people matters are significantly improved if they press Refresh in their browse. If you're using Firefox, try pressing Shift+Refresh. At about 4:30am this morning after many hours of work, that made the classic option work well. Only a couple of minor layout issues remained.
Text is not meant to be squished, you're not supposed to have to scroll down through acres of whitespace. We'll definitely fix these issues.
I've no idea why people are finding text too tiny; the font size hasn't changed intentionally, so if it is tiny for you it's either a need to press refresh (to reload the style sheet, in tech speak) or a problem that will be fixed.
Threads I'm On and Threads I'm Watching should behave in the way they always did - they do for me. Let us know the specifics of problems you have with them and we'll address them.
We know about the problem of seeing "hide hide hide" across the top of the page. If you go in to customise (which my huge ENGLISH dictionary lists as being able to be spelled either customise OR customize) you can turn off showing of the Hide option which is a workaround for this problem. We'll fix it properly soon.
The ads have neither changed size nor increased in number.
Remember: Press REFRESH (and try SHIFT+REFRESH) a couple of times. It might help a lot.
For those having problems we do apologise and will sort it all as soon as we can. For those that hate it, perhaps you'll get used to it after a while and we'll improve the classic options (though I am using them now and they're working fine).
Oh and for the 2 of you that said thanks for all the hard work: thanks! It has taken over a dozen people a lot of hard work. We had to release it in a hurry and it's not perfect, but we'll get there.