It looks like Himalayan Blackberry.
They are an introduced species and some places count them as an invasive weed. They were introduced to North America in 1885 by Luther Burbank.

I love the flavour, but like Doug says the thorns on the stems are murder.
I remember places where they were so thick it would have been almost impossible to go through them and had to go 1/4 mile to get around them.

If you want to grow them it helps to cut out the older stems and thin them into rows.
You get more berries because you can reach them without getting clawed to shreds by the thorns and they only produce berries on the second year growth anyhow.
Because they only produce flowers and fruit on the second year growth the canes can be cut out on a 2 or 3 year rotation and still supply the same number of berries but on much shorter canes. Shorter canes mean fewer thorns and less tangle.

I found the best way to thin the canes was to just mow roads through them with a whipper snipper and/or a lawn mower. I used to cut my rows on a 3 year cycle.
Cut one line for a walkway, one line growing this year and one row producing berries. The row that produced berries got cut in the fall and walked on the next year.
For smaller patches I used either a pole pruner like they sell for tree trimming or a hooked knife on about a 6 foot handle. The blade on the hook knife is not very big or thick and the hook can be a simple V notch filed or ground into it. Cheap steel is fine.
You work it by hooking it behind the cane and pulling it to cut the cane off. The long handle on the knife or the pole pruner lets you stay away from the thorns.

If you need to get rid of these blackberries permanently it can be a real chore. You need to get rid of any living roots too or the canes just sprout up again thicker than ever.

One of the few places where herbicides are justified in in trying to kill out a blackberry thicket.