The reviews really are this good. I had an excellent experience.
I had originally booked a Toyota Camry, but got an upgrade to a lovely Mercedes GLB.
The staff were excellent, particularly the gentleman at check-in.
I got an excellent deal having booked online, and it was much cheaper than what was on offer at Pearson. The UP Express from Pearson to Union made it really quick and easy, though some walking is involved.
I will definitely be renting from Sixt next time I am in Toronto!