It's both many times faster than booting from microSD, and unless you buy the absolute cheapest SSD from a no-name manufacture, many times more reliable.
Additionally, if you have a good power supply and don't write tons of data on a daily basis to the microSD card, it will be quite reliable as long as it's a name-brand, high quality card.
Source: I've deployed about 50 RPis in various conditions, all but two booting off microSD cards, and have only had one failure requiring swapping in a new microSD card, over the past 8 years of use.
Industrial microSD cards are especially robust and are now available from a variety of manufacturers with environmental and wear ratings that rival decent SSDs.
