There's always the Beyoncé fans who would immediately buy it anyway but I think it's both. A large number of purchases would have been a result of the massive hype (I've seen a few comments suggesting they bought it just because of the hype), and a good number because they liked the music. I say that because, you can preview 20+ minutes of the 65 minute album on iTunes (definitely enough to see whether you like the sound of the album) and it's received critical acclaim so I don't find the last option hard to believe. Critics aside, I've seen many comments across websites praising the album so yeah. I think it's both.
There has been another album with a stronger opening week (The 20/20 Experience: Part 1) so I wouldn't worry just yet.
Honestly, I think it'd take a number of years for an album to reach 100,000,000 sales (keeping in mind Thriller, 104million copies as of 2006, is roughly 40-50 million copies ahead of the second best selling album of all time). So it'd surely take a good number of years, perhaps decade, maybe even two. Who knows speciically, all we know is that it'd take years ^_^
I think it's pretty decent! I like to play an album a few times before I give a final judgement (as I find a number of albums take a few plays to get used to) but so far I've quick enjoyed this album! I'm not sure if it's my favourite (which atm is either 'B'day' or 'I Am... Sasha Fierce').
But yeah, it's definitely a very solid effort in my opinion