In the leaked documentation, it cites that approximately 97% of third-party apps will be able to run on 512MB handsets, although a handful of them will remain in a dormant state when you switch away. In other words, seeing the “Resuming…” screen will be made all the more common, and a mere pair of tabs of memory-intensive websites will remain in memory, as others will have to take the reload express.
As for HDR images, those too, will be of lower quality since such lower end devices are able to capture a trio of 5MP shots, as opposed to five 8MP ones.Other limitations that one might have more cause for concern would be navigation apps, and while tracking location remains possible in the background, it will not remain that way when active apps use up too much memory. Do bear in mind that these issues mentioned are meant for legacy devices, as the newer range of Lumias like the low-end Microsoft Lumia 430 itself sports 1GB RAM right out of he box.