Before I begin with my reply, I want to state that I have not yet had a chance to play the final game, as I am not in the EA early access program. My opinions are based on my impressions of the beta, and the text list of nerfs and buffs that the developers posted a while back.
In regards to the Imp, I definitely agree that they went too far with the nerfs. I was ok with the health reduction for the mech, as dealing with multiple mechs at the same time seemed a bit overwhelming / OP. A slight nerf to the range of impkata might have been ok, but other than that, I don't think the imp really needed any nerfs outside of the mech. He had sort of a glass cannon sort of feel, but now he just seems really weak.
In regards to Rose, I think the damage buff they gave to her was justified. Rose's damage output just seemed really lacking in the beta, and she had to work hard to get kills. She seemed like a pure support character, and while she is quite good in a support role, I think giving her a little more punch will allow her to be a more satisfying character. Without this, I don't know if she could be a viable character in modes outside of Gardens&Graveyards. As far as her other buffs go, I'll reserve judgement until I get my hands on the game. If at some point they do decide to nerf her, I they need to be sure not to go crazy with it and make her even worse than she was during the beta.
For future balance changes, I really hope that the developers make more modest adjustments. If they think a character is still OP after nerfing them, then they can go back and take a little more off the top, so to speak. The nerfing of the Imp is a classic case of developers making a kneejerk reaction due to a vocal segment of players that likely don't really understand the game.
All that said, I think most of the other nerfs/buffs for other characters sounded quite good and I think they did well overall. I'm really looking forward to playing the game next week 😃