Ultimately the Surface Pro 9 is worth buying if you're looking for a tablet with 5G support, and opt for one of the SQ3 CPU chip 5G models, or if you're looking for a device with more processing power than the Microsoft Surface 8 can provide.
If you don't fall into this category, then we'd suggest you instead consider getting a Surface 8 deal this Black Friday, and save yourself a substantial wedge of cash.