If it really is crack free, it could be a good score! I've been looking at a fair number of ads on Craigslist and the fb marketplace. Most of the barn wood or thick cut mantle boards have significant cracking through them. That price is very good compared to what others are asking.
If it does have cracks, it should be good and stable for experimenting with epoxy.
Dry hickory is going to be really hard and will give you lots of practice sharpening your tools. Hickory is about 50% harder than oak, which is closer in hardness to maple. If it's anything like the mockernut hickory I have been turning chunks of for a while, it can have some really nice colors and contrast between the sapwood and heartwood. I turned a bunch or red oak I got from a neighbor's tree last year. Oak's coarse, open grain is different to work with and it had neat color and character through it also.