Amazon MCF: US Fulfillment

I have been using the app for about 2 months in order to have all of my Shopify orders fulfilled by Amazon. The connection of SKUs was simple and once connected, it seems to be robust. I am in contact with direct Amazon support for technical issues and they are working on fixing any issues I come across, which seem to be minor.
I give it 4 stars at the moment mainly due to the customer support for logistics issues when an order arrives late or never shows up or other issues related to getting the product to the customer. When we come across these issues and have to contact Amazon support for refunds, it is way too much back and forth with overseas support when it should be much more streamlined if issues need to be resolved. If a customer states that an item never arrived, we should be able to get a full refund for the cost of the product and the associated fees for MCF, or Amazon should send out a replacement to the customer at no charge and refund us the cost of the product. This should not take a dozen back and forth emails to do so. Also, if a customer pays for expedited shipping but arrives a week late and the customer wants a refund for their shipping, it should be easier for us to request a refund from Amazon as we do not want to eat the cost due to Amazons fault. I hope that they provide better support for MCF customers soon.

Well, it's been working again as long as it wasn't syncing inventory or pushing orders through so that's good. Unfortunately getting the attention needed to fix our issues after two weeks of not-useful tech support exchanges took a one-star review. Not the best takeaway but at least now we know how to get on the devs' radar.

So still promising and easy to integrate but use caution until all of the bugs are ironed out. In the meantime, if you do install keep a close eye on things to make sure orders are actually getting pushed to FBM and you aren't over-selling out of-of-inventory SKUs.

This app is relatively bare bones but is quick and works well.
Ideally I would like to see the following updates or improvements.

1. Ability to change MCF shipping speed after the order has been placed by our customer before it is submitted for fulfillment. If the MCF shipping speed was displayed the same way it is on customer checkout that would be great.

2. Display the cost of the MCF shipment in the Shopify order

3. Display the expected ship date and delivery date in the Shopify order

inventory count is not synching????!!!! please fix it asap!!! everyone did the switch and the fact that inventory count is not synching is a big problem after the switch!!!

This app doesn't really work at all with a merchant account that has multiple stores. It doesn't let you pick the right account, doesn't let you change things if it picked the wrong one somehow, tells you to disconnect the account first before trying to link a new one (but gives no way to do that), is buggy and doesn't let you connect products, etc. It's absolutely not a "best in class" app like they claim it is, even the wording on errors/messages is unclear.

Does not Allow to have multiple shopify accounts connected, you can only use one. the old method allows you to create fulfillment to multiple accounts.

It would be nice where a note is placed before downloading that the app only supports Amazon US seller accounts only!!
In today's market I wonder why Canada is not supported?