My honest opinion:
The launcher itself is fine. Friends stuff doesn't feel quite there yet (the one thing about steam is it is so easy to do things with friends, like invite to watch your game etc). That's a minor niggle though. The store always seems very expensive, so I've never bought anything on it. You'd think publishers might consider lower pricing thanks to the lower cut from Epic, but I guess not.
The free games are occasionally great, but mostly aren't my jam, so I am not super fussed about it. Would I have epic installed if it weren't for the free games, though? Probably not.
The absolute core reason I don't think I'd migrate to epic? The vast majority of my games are on steam. The vast majority of my friends are on steam. In the short time I have in the evening to play games, I want to just have a look at my installed games and play the one that I feel like, or that my friends are playing. It would take some pretty bad management by Steam to get me off of it. Like if they started charging to have an account.