It really shines in the first few shuffles if you can either delay or skip Silver, which is certainly enough of the time to be worth noticing. I think I’m a bit biased against it in games where you have to open Loan / Silver, sort of the same way I’m biased against Sentry: you really remember the bad luck games where you hit your Treasure repeatedly. That said, especially if it’s one of the primary trashers it’s worth jumping through a few hoops to avoid Treasure early on, and since it’s a non action trasher it makes terminal silvers more appealing.
I like it best paired with $4 cost trash for benefit, like Salvager or Remodel, cards that would prefer to not trash Copper. But it can supplement most trashers on the right board for it. You just have to be fairly sure you don’t need Treasure cards for the first few shuffles.
Two Loans is okay, sort of similar to two Lookouts, but I don’t often do this because of how quickly it drains your economy. It does let you get in more trashing before you are forced to buy Silver if you’re sure you need it in just a couple of turns. Hopefully one gets the other but not too soon.