Software is absolutely the strength.
The extraordinary social impact of iPad on education, bringing technology and books to the masses, especially the non technical, education and entertainment to the young (who can use this device even before they can read), the elderly and most importantly the enablement of the disabled are the greatest achievements of the iPad. This is the device of the 2010's.
Focussing on something like multitasking in the OS is really narrow and misses why this device even exists.