Is this a good build?

Very good budget build.

PCPartPicker part list / Price breakdown by merchant

CPU: AMD - Ryzen 5 2600 3.4 GHz 6-Core Processor ($164.99 @ Amazon)
Motherboard: MSI - B450 TOMAHAWK ATX AM4 Motherboard ($114.89 @ OutletPC)
Memory: G.Skill - Aegis 16 GB (2 x 8 GB) DDR4-3000 Memory ($99.99 @ Newegg)
Storage: Seagate - Barracuda 2 TB 3.5" 7200RPM Internal Hard Drive ($59.89 @ OutletPC)
Video Card: Sapphire - Radeon RX 580 4 GB NITRO+ Video Card ($189.99 @ Newegg)
Case: Phanteks - Eclipse P300 Tempered Glass (Black) ATX Mid Tower Case ($55.98 @ Newegg)
Power Supply: EVGA - SuperNOVA G3 650 W 80+ Gold Certified Fully-Modular ATX Power Supply ($59.89 @ OutletPC)
Total: $745.62
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2019-01-11 21:17 EST-0500
 
Solution
I agree with SR-71's suggestion that you should swap the graphics card for an RX 570 or RX 580, just because they are significantly more powerful than a 1050 Ti. At current prices, I would only consider a 1050 Ti if the card were being installed in a prebuilt system with an inadequate power supply.

An RX 570 can be around 50% faster than a 1050 Ti, and an RX 580 around 70% faster. Plus, it's possible to find them bundled with download codes for some big upcoming game releases.

And you really shouldn't pay twice as much for a WD Black drive. If you want to spend over $100 for more drive performance, go for a 1TB SATA SSD, which will significantly reduce load times over a spinning platter drive. Or a "regular" 1-2TB 7200RPM drive, along with a 250-500GB SATA SSD for the OS, applications and most-played games. Something like a Crucial MX500 would be a good option.

And that Phanteks case looks classy. : D