I have both and thinking of returning Fire. Watching my own videos is not intuitive as compared to iPad 2 and eReading options are very limited in fire. For example I read graphic novels in CBR format (Comiczeal app), screenplays (fdx reader), ebooks (both epub and mobi) and PDFs (good reader). Even 50% of these activities cannot be performed on Fire without workarounds. Off course your buying decision depends upon the usage. I described what I typically do on iPad to give you an idea if any of these activities follow your usage pattern as well.
iPad 1 (Goodreader, FDX Reader, iBooks, Bookman)
iPhone 4 (iBooks, FDX Reader)