Lots of problems, design and functionality both
Calendar: when you converted your calendar a while ago, all long term reminders (once a year - birthdays, anniversaries, yearly reminders to renew various contracts etc.) got lost. You just either lost or forgot the old database of reminders! Is it so hard to write a script to reschedule this?
Email. Awful awful and more awful. Slow. When I delete an email, I get back to the Inbox/folder view, but the deleted message is still visible for a couple of seconds. This means that if I don't wait until it's gone and click on the next message I want to view, I get a different message since the Folder list is "offset" by the presence of the "zombie" message I just deleted.
Also, when opening a message, scrolling with PgUp/PgDn doesn't work. Not everyone read emails on a mobile device!!! Any new design should be backward compatible for desktop users!
- My Y! Shameful!!! Your designed should be fired and never let anywhere near a website again. Boxy, huge, uncomfortable to read. Even after I selected the smallest font, it's still too big.
Both columns are the same width - very uncomfortable. Narrow modules/channels are now taking more space than they need, and the wide ones don't get enough space horizontally, so they stretch vertically.
All the modules/channels and feeds I had on My Y! got rearranged in almost a random order. I can't find anything. Order MATTERS.
Your style sheet doesn't support a different coloring for visited links. I used to see at a glance what's new in each channel - the new links were in a different color. Now I have to review each link separately.
When adding a new RSS feed to My Y!, it used to ask which page I want it on (I have multiple pages). Now it just dumps the new channel on Page 1, and good luck dragging and dropping it to another page. Took me 3 tries.
Channels got "downsized" to 3 top titles instead of 5. Bad for news feeds.
How was this abomination released to production??? Do you have a QA department?