I just want to second what Another Reader said. Assuming you are part of a non-governmental hospital, the 457 assets belong to the hospital, not you, until the day you actually receive them. If the hospital fails, you have to get in line with the other creditors to get what's left of "your" money.
In your case, my advice would be to make sure you have maxed out all of your other options - 403(b), Roth (including backdoor if applicable), etc. before contributing to the 457.
If you work for the government, then I understand the 457 is structured differently - the money is held in trust for you, so you are protected should your employer go bankrupt.
You might also want to clarify the issues around roll-overs:
Governmental 457 plans may be rolled into other types of retirement plans with few restrictions beyond the normal ones for any other type of employer provided plan, which includes separation of service or disability. This includes other 401(k) and 403(b) plans and also IRA's. IRA's have much greater flexibility in withdrawal and conversion privileges. In contrast, non-governmental 457 plans can only be rolled into another non-governmental 457 plan.
I was hesitant to defer any of my comp in our hospital's 457 plan for the reasons above, so initially I didn't put anything in the 457. After thinking about the value of the tax deferral I came up with sort of a compromise. My current plan is to first invest in qualified plans, then contribute to the 457 until my 457 assets reach $100,000. So far, our hospital's financials are very strong, but as you know, there are huge winds of change sweeping across the medical system. With value-based payment schemes and more on the horizon, money will likely be moving away from traditional hospitals toward ACOs, medical groups, or other outpatient provider organizations (which is why hospitals are buying up outpatient practices)... I don't want to have my job and a huge chunk of my assets tied up in the same organization if things go bad financially. If the hospital's financials start to go sour, then I will hopefully have enough of a heads up to quite the job so I can pull my 457 money out.