I give you that lack of multitasking is disappointing (Flash not so much though). But your criticisms are software features and I think multitasking will be one of the new features on iPhone OS 4.0.
Although iPad can be thought of as a large iPhone (or a bit more accurately, large iPod touch), some may also say iPhone is a super small notebook, or that it represents a small iPad.
Yes, iPad isn't a revolutionary device like iPhone was, but if you were to design a tablet computing device, and want to make it as cheap as possible (starting at $499), what would you do all that differently? Apple took the iPhone OS, enhanced some of the apps to bring some of Mac OS X apps functionalities while adding new features of its own (e.g., iBooks).
Like the original iPhone, the platform will evolve and for me, I think it may represent a better browsing experience (sans Flash-based websites) than Mac OS X.