An attorney's fee is usually 1/3 of the settlement plus his expenses.
Insurance adjusters are not afraid of attorneys - no matter what the tv ads say. Adjusters deal with attorneys all the time.
A settlement offer is based on your injury. An attorney's fee is not a consideration.
Is it worth it? Only you can decide if it's worth it to give an attorney 1/3 of any settlement you get.
You probably won't get an attorney willing to take this on a "no win no fee" basis. There's not enough money in it. If it happened in a "no fault" state, you don't get any pain and suffering, and you might not get any medical bill coverage.
Insurance companies usually settle pretty fairly, the problem usually is that the people don't understand the tort laws in the state, or have an unrealistic idea of how much money the claim could be worth.
Oh, and "personal injury" means slander, libel, defamation of character, false arrest. You're talking about BODILY injury, not personal injury.