I think that I've saved several days time in trips to Lowe's and Home Depot by frequenting this small shop. The store is small enough that finding things is a snap, and the staff is quick to offer help (and for how young they are, they're surprisingly able to help.) Their selection is pretty comprehensive, but if you're looking for just the right light fixture or faucet set, I'd start somewhere else. If you're looking to replace a gasket, or some kind of weird-looking bolt you've never seen before, this is THE place to be.
There's seldom a line, and only a very small parking lot (which is rarely full) so getting in and out is quick. I find their prices to be very reasonable.
One of my favorite things about Ace Hardware is being able to fill a propane tank there for $12. That's three or four dollars less than exchanging a tank at Walmart.
I also like the "real hardware store" feeling of Ace. Kind of takes you back.