I just like how it is so complete. It provides everything I need! The website, inventory tracking, payment processing! It works both for online sales and POS and the inventory amounts are all synced. Really high quality as far as I am concerned.
I wish it was cheaper for when you don't have very many sales but the price is actually not bad. Not a lot negative to say.
This is such a standard and complete software, it is hard to beat. Pay attention to their customer support hours. The reason I chose Shopify is that they have 24/7 report so it works if you are starting it out as a side business. You don't have to take time from your day job for a customer support call.
It makes the website and I always know exactly how much inventory is in stock so people don't buy it if I am out. It basically is the whole business in one little platform.