I'd look at the Lumia 820 instead. It has the same 1.5 GHz processor as the Lumia 920 and 1 GB of RAM and 8 GB of internal memory. Its considerably less expensive than the 920 too. It costs a bit more than the 8S, but hopefully within reach for you.
The 8S is just too compromised to be useful in my opinion. 4 GB of memory total actually only leaves you with about 1 GB or less to use for apps. Not nearly enough. You cannot run apps from the SD card, so that will not help you. The 1 GHz processor is adequate, but not great. 512 mb of RAM is the same, in fact there are already WP8 apps that require 1 GB of RAM and there will be more coming.
Why would anyone want a phone that hardly has room for any apps and won't be able to run the best apps and games?
I would try your best to save and buy the Lumia 820, you will be glad you did.
If there is just no possible way you can buy the 820, then I would wait for the Lumia 620 which is coming soon. It has 1 GHz, 512 mb RAM like the 8S, but it at least has 8 GB of internal memory vs. only 4 GB in the 8S, so at least you can have more than 5 or 6 apps. Also with the 620 you get all of the Nokia exclusive apps, plus Nokia support and updates, which are proven far better than HTC on Windows Phone.
The Lumia 620 should be along very soon and will be priced about the same as the 8S. It may even be slightly less.
Try for the 810/820, if there is no way you can afford it, then get the 620.