I've had mixed but overall good experiences with them.
Last year through this spring, I've ordered probably 50-60 fish through them, some ORA, some California, some Wisconsin, no DD. Probably half the total numbers were freshwater fish.
There have been a few DOA's, but they upheld their guarantee and offer full credit every time. They also subtract the credit values on orders after applying toward the total needed for free shipping, so it is a 1-to-1 replacement except for the disappointment of DOA.
Most fish have shown up alive and healthy.
A few notes:
On one freshwater order, I specifically ordered hillstream loaches for the type I wanted as they specified with the scientific name. When they arrived, I actually received a different species than was ordered (and a species I did not want), and 5 of 6 showed up dead and half rotten. This was one of my worst experiences with them.
A couple times, I had a larger (3-4") fish show up DOA while appearing healthy.
I've definitely suspected gill flukes on the fish in several of the orders. I have not seen long term affects after a few rounds of PraziPro.
My most recent order included most of the fishes in my work tank and I am fairly certain they showed a moderate outbreak of Cryptocaryon (ich/white spot). Symptoms dwindled away through a month of dosing Ruby Reef Rally Pro and Kick Ich in addition to PolypLab Medic and symptoms have not returned over the past few weeks after dosing.
There also was an order that they held back due to not having all the fish for the order. I specifically communicated to them a few dates that would not work for me for the shipment if the fish did become available, including a Friday that I would be travelling and not at work to receive delivery (I have fish deliveries brought to work so I can meet the courier and receive delivery immediately). Even after using the online chat in addition to emails to communicate that date would NOT work for shipment, they scheduled the delivery of a Merten's Butterflyfish for the Friday I was travelling and could not reschedule. When I called to discuss the issue, they said nothing could be done about it, but, if I found the fish dead on Monday morning when I returned to work, it would still be guaranteed with their arrive-alive or 7-day guarantee and I could get a full refund (who cares about the fish that will die after 3+ extra days in a shipping box due to their mistake!).
Thankfully, I was able to set up a QT at work before I left and spoke with a co-worker who had some saltwater fish experience about receiving the order for me. All went well for him, and the fish made it healthy and doing well after all. Still, not a great experience with LA customer service, IMO...