Here is a tip for anyone who has a tough time.
Remember you are not Cole McGrath.
This means you aren't comfortable where Cole McGrath is.
This means hanging from ledges isn't your style.
This also means your battle style and strategies have changed A LOT.
(if you are new to infamous, then at least onsider that delsin's battle styles will greatly vary when switching stuff up)
As long as you consider that you are one person against an army, do what you normally would if you were in that situation. Take cover when you need it, switch powers and drain resources when necessary (even if it is just to give you health). From there just freestyle your gameplay, but keep it rational.
Expert really wasn't that hard, for me anyways, it was actually more fun to have to think out a few battles more carefully, although I did Evil Karma on Expert so I didn't have to be SOOO carefully and earned Karmic Streaks fast and use those A LOT on large battles, lol
I thought the game had it's difficult parts on Normal, while playing the Good Karma. I kept thinking "Wow, it's going to be hard on Expert." NOPE. Playing Evil on Expert was easier than I thought it would be. Especially since you're just destroying everything and everyone you see and not having to worry about accidently killing civilians / DUP soldiers in battle, like the Good Karma playthrough. You are an absolute monster, if you play as Evil Del.
I can only imagine playing Good Karma on Expert -- that is probably where the real challenge is.
If you are doing a Good karma playthrough, Neon is your bestfriend. It allows you to slow dwn time and subdue enemies quickly, allowing you to build up your karmic blast pretty quickly. If you are doing an Evil karma playthrough, smoke if your bestfriend because it is extremely destructive. Upgrade your missiles to full capactity and use them as much as you can. Smoke sources are very easy to find especially when everything is already blown up around you.