Our medium sized site in Drupal for Books and Educational Toys for India

We started last year in Mar 2011 with the aim to building a medium sized eCommerce site offering upto 500K products in the initial phase with the catalogue of mainly Books. Toys and Educational Toys. We already had a toy site built on Drupal by our developer so we were fairly confident that building a new site would be fairly simple.... but I guess you can sense the but coming :)
It was fairly easy to build up the initial bare-bones site, Giftsmill.com with a simple theme and only took about 1 week since we had based it on our earlier site. To say that we were amazed by the simplicity of getting up and running was an understatement! We had a test site linked up with PayPal within the first month. After the initial test site though, we did have to put in a lot of hard graft to get up to speed with the new-er modules and the sheer difference in size of the new site.
The most painful part for us was the custom uploader we had to build to import the vast amount of the product specific data that we had to load the site with. With hindsight, we should have just built a new module, maybe when we upgrade we will build a module to upload book data. The other thing that caught us out was the site wide search and it took us about a month to fine-tune.
The non-technical issues we faced were more painful and were the bureaucratic process to get a payment gateway in India and eventually it took us about 5 months to take our first test payment.
Hope this post will provide a little bit of an insight to others hoping to embark on the journey of building an eCommerce site.
In summary we were very happy with our decision to build with Drupal and Ubercart and are planning to upgrade to Drupal 7 to get the Schema.org functionality.