At this point I think Carter is dead but the actor will be around for flashbacks. I am happy with this.
I like Kendra's character when she was on the Flash, but so far they have not used her well here. I would love a character that is exploring her past and taking to heart the advice that Cisco gave her, but so far there hasn't been much of it.
Jackson has potential, but so far he is drastically underused. It would be really cool if they get into the part where he wanted to go to college but couldn't, and now he literally mind melds with a professor. I like that they have not made him an idiot, as shown in the 1 scene where he actually got to do something (go fix the spaceship). I feel like they can really grow him into the link between the jocks (Captain Cold, Heatwave) and the nerds, if they let his character get some confidence. It could be a great character arc, if they give him enough screen time to actually do it.
Heatwave seems to exist only as a foil. I think he is necessary, but hope they actually do something with him eventually.
I think Sara has been awesome. Stein and Captain Cold steal the show. Palmer is fun.