I'll have yet to try Swain out with his nerfs myself, but it looks like Riot has ruined him for me
Disclaimer: I'm not some FOTM player who randomly picked him up. I've played Swain a long time and have 2 of his skins. I have over 50K points on him and mained him before the mastery system was implemented. I love his lore, his theme, his gameplay, his look, his personality, and his skins.
They have changed Swain's gameplay very much. They broke him like Morde, and now I have to pay. I'm hoping I'll still enjoy him but his ult was his key point. Part of Swain's identity was having 4 abilities and no ultimate. It would be like buffing Udyr's tiger form, but giving it a much longer cooldown. I wish they would revert all the changes to his ult, it seems like most of his problems come from that. His Q and E changes were fine. I just hope I'll still enjoy the Bird Man after Riot throws him away, to get a rework in 2 years.