There are some possible problems but also some potential.
Some Aldi's are just nasty and you never know if you're going to get a good one or one of the nasty ones until you're there.
Some of their food is very good and some is very bad, but that also depends on your personal preference. Really what I used to do is if I wasn't sure, I'd buy one and try it out. If it was good, next time I'd buy several. But that's easy to do because it's not 45 minutes away. And I think the suppliers might be different depending on where you live? I remember posting on some forum a long time ago about Aldi's canned green beans the whole can was just the "ends" and awful, and someone else said they'd never had a problem with that and their canned green beans were perfect.
45 minutes means you'd need to take a cooler for anything frozen or fridged, which is some of their best stuff.
The good stuff: You can stock up for cheap! If you're up for buying a whole flat of soup, you know, someone who buys in quantity and knows what to do with it all, you can save some big bucks. And as such, if you could plan to go there once a month and do that stock-piling, it would probably even out on the gas. I don't know that I'd make a special trip because you'd have to buy a whole lot to make up for 1/2 tank of gas.
The whole bag-your-own and 25 cent shopping carts are not a biggie. Ours always has boxes and they have a counter for you to use to pack everything up.