iDeaS Emulator used to be one of the most popular emulators, however it has recently fallen out of favor due to newer releases. Still it maintains a core following, and can run many NDS games. This emulator utilizes an OpenGL renderer, and as it can emulate the ARM7 CPU completely, it has the ability to emulate GBA games.
The iDeaS team is even working on emulating the ARM9 dual screen processor. Although they have claimed 99% completion for some time now, this is a feature still uncompleted. So although this emulator can run games that require the ARM9 dual processor, there is still no completed bug-free version.
iDeaS comes with a plugin system that is unique among emulators of its type, so developers can add extra support without needing access to any core code. While that might be a great feature in theory, this emulator’s lack of popularity means there are very few developers actually utilizing this feature, rendering it useless.
This emulator comes with all the basic features you expect from a completed emulator, such as portrait and landscape mode, save options, and graphics acceleration. Beyond these basic features, iDeaS does not offer much advantage over any other emulator, and is quickly being depreciated.