Yahoo mail's make over gave a little breather for long time loyal users like me. Its still leaps and bounds behind Gmail (or for that matter the new outlook.com), But at the very least, the UI developers managed to cleanup a major issue with its header space management.
They managed to get their act together. moved the controls around and saved at least 20 precious pixels. The controls-unified header now totals 50 px (still high, but) considerbaly less annoying than the previous one which was upwards of 70 px.
The tiny menu items up top are converted to a smartphone style menu icon, which shows more options on a hover popup menu. Over all, it looks slicker. But still is a turn off to look at especially in x-wide screens, where it takes up more space on a percentage basis.