I bought a new bluetooth mouse last week as my several year old Apple Magic Mouse 1 finally died.
Bought a Microsoft (gasp!) designer bluetooth mouse as it is much cheaper than a new Apple Magic Mouse 2 and I think it looks quite good (simple and branding is subtle) and it works well (only had it a week but I use it all day, everyday for work).
Have had no issues with bluetooth connection, no lag, it rolls smooth (I use a mousepad), and there's no ugly usb dongle.
I like things simple though, there are much more complicated mice out there but they're not for me.