If this goes through, I will be a full-time Google/Gmail user. I left MSN for Yahoo! because I hated MSN and Hotmail. I wonder if Yahoo (enough with the exclamation point) ever commissioned a study to see how many of their users were MSN refugees. If this merger happens, I expect Gmail usage to surge.
In semi-protest I canceled my Yahoo Premium service. Using the "new" Yahoo mail client without the protection of Premium's ad elimination is a trying experience. It is a fugly looking creature with all the ads. It also seems slower. In fact, I've had to switch to "Classic" to retrieve emails that just couldn't seem to come through.
Gmail isn't pretty either, but it is not nearly as trashed with ads as Yahoo "plain".