I use Gmail for my mail needs and they do a very good job at making things useful, but two things they are pretty bad at (actually 3).
1. Google’s address book is pretty bad compared to most other things they have. It’s at least a decade behind in smart and finesse, but since I dot need add and remove people here daily I live with it.
2. The Calender is a part of Google mail and works ok, but they have this annoying bug. They have decided that they know better which birthdays I want on my calender than I do. I somehow can’t get it – I like the idea of smart-you-name-it but mostly it needs training. Maybe I don’t like birthdays because I’m born the 29th of February (you never know). There got to be an option for “that”.
The third thing Google is pretty bad at is G+ – nothing wrong with G+ on it’s own accounts – but in the early days they polluted address book completely with G+ people I follow. It took me hours to clean up. They are btw still there (which annoys me) but they seems to stay out of the way for the most cases. The same for the birthdays above – the G+ people are really my problem. I don’t have a connection with these people to the level that my calender need to be infected with them. Now if I could delete them (mark then as ignored) I would invest the time in doing so – Gmail and Google Calender is free after all.