I've experienced Fahrenheit Coffee two ways - in their cafe and by taking their whole bean coffee home. Both are exceptional.
In the store I had a cortado (ask them, they love to explain it) and an americano. Both were really delicious - the cortado was sweet and roasty, but the americano had all sorts of delicious citrus and fruit notes. (If you don't drink a lot of coffee, just trust me that those are good things, even if you want to add milk.)
I have had (I think) four different roasts from them brewed at home and all of them have been delicious and distinct. They have smooth, flavourful and delicious light roasts that coffee lovers will appreciate. (If when you think "light roast" you think "Tim Horton's," for heaven's sake, get in here so they can set you straight) as well as delightful espressos.
And I'd be remiss if I didn't mention that this is, by far, the friendliest coffee shop I've ever been in. The guys behind the counter clearly love their jobs - they were laughing and chatting up customers and cheering for regulars the whole time we were in there. There are a lot of coffee places to visit in Toronto, but this is one of my favourites.