While I have been known to come here once in a while, Mel's really isn't all that. I have always found the service lacking here. They're slow and hard to flag down. Their breakfast is often bland and their deli sandwiches aren't anything special.
The two food exceptions about this place is the Montreal Smoked Meat, and the Eggs Benedict (which is made with Montreal Smoked Meat.)
The real saving grace of this restaurant/diner is the fact that it's open 24/7. It's a viable option at 4am when the whole world is closed and asleep.
For the most part, I consider Mel's to be a bit of a last resort. It's nice to have a 24hour diner on Bloor, because there really are days when you're thankful for it. But most times if there's another option, I'll take it.