At first I didn’t care much for the Uber metaphor, because it's not accurate (it turns out, less than 20% accurate), but I’ve warmed to it, to convey the gist to the listener.
We had a mobile-first product, and while getting ad hoc snow plowing is useful the day of a storm (and from the supply-side, mobile solves a problem), most of our business is from repeat customers. That is, snow plowing is a route business, and mobile is a companion (e.g. for one-timers, to get info. on your plowguy’s eta/location etc).
Like others, I find the Uber metaphor useful for telling people what we do in 3 seconds, though interestingly, it’s hardly ever to customers. Most of our customers have never heard of Uber in fact, probably not a surprise given their age (many 55+) and where they live (suburbs). I imagine this is different than other Uber for X companies.
By the same token, I find it helpful to invert the Uber metaphor to further explain what you’re doing. For example, Uber would be like PlowMe if it had the option of picking you up at the same place and time automatically.