Aluminum is not as slick as brass, so extraction problems may happen in some firearms. If they gave it a light coat of polymer like many steel cased ammo now, it would be less likely to cause issue.
That said, most firearms will shoot it just fine.
Aluminum is weaker than brass so no reloading can be done. And guns with chambers that are on the loose side of the spec may allow some splitting to occur.
I have seen aluminum cased ammo with nylon jackets... And I thought... If it had been significantly cheaper than brass, like a little cheaper than steel cased, I would shoot it.
If it was the same cost as steel and copper jacketed, I would buy it up like crazy for days I don't want to chase brass. Because most steel cased ammo has by metal jackets and that can cause more wear of rifling.
The aluminum cased and nylon jacked bullets I seen were the same cost as the good foreign made brass stuff... So too much.
It eliminates the two most expensive parts of the ammo... The brass and copper used for the case and jacket... It should reflect that in price. Aluminum is cheaper than steel even. Heck, you would think nylon being very slick overall would help give barrels longer life, so if they shoot well, its not really a bad thing.
I am not a stickler for tradition if the new way works as well or better, more so if I save money. And while aluminum cases are not perfect in every gun, its reliable enough overall to be worth merit. Too bad its not used more often and has a price to help sell it in a market that likes tradition more than it admits.