Barely faster than your standard HDD. I'd wait it out for SSD to get slightly cheaper. The prices on these drives have been falling dramatically over the past few months. This one in the link originally was 700. Now it's 270 and with a 2 year warranty I think. It's all pretty rugged and won't break from a fall.
These have a really nice design to them, too. For reference, look for local equivalent:
https://amazon.com/SanDisk-4TB-Extreme-Portable-SDSSDE61-4T00-G25/dp/B08RX4QKXS
Make sure to get the NON 2x2 version, because Mac can't take advantage of that. Wish SanDisk had a Thunderbolt version, too.