Posted this to BGG, I see no reason not to post the same content here, even though some of it people have already talked about.
The card itself isn't the most exciting, but they can't all be, right? $5 cantrip +coin with a bonus is a fairly normal thing (Market, Treasury, Highway, Junk Dealer, Bazaar etc.), so this fits in there. I'd say it might be about average with those, but I'd really need to see just how valuable saving the coin is. Normally, early buys matter more than later ones, so you probably want to use that coin token soon-ish. Then again, there's lots of possible tricks you can do with them to know just how good it is.
What this card really shakes up is the openings. 5/2 openings just got even better, with a 6/2 opening being a thing. Hello, turn 1 Gold. Or Gold/Chapel or the like. Of course, 4/3 can keep up with 5/3 openings as Donald Mentioned, and occasionally, a 4/4 opening will be a very strong thing. Normally though, I expect 5/3 to be better. If there's good $5's on the board like Witch, Mountebank, Wharf or the like, 5/3 might even be better than 6/2, actually. Either way, one thing is for certain: This card's mere presence is going to lead to faster games on average.