Facebook agreed yesterday it would buy the instant messaging service for $19bn, in a move that would give it access to 450 million monthly active users.
While Mark Zuckerberg reassured users that WhatsApp would remain as a separate firm, analyst firm IDC has warned the core WhatsApp experience must remain the same in order for the deal to be successful.
Alys Woodward, a research director of predictive and social analytics at analyst firm IDC, told CBR: "Facebook has to keep WhatsApp as it is...the attraction for users is more that it doesn't advertise.
"People use it because it works and hasn't got ads. If you're instant messaging with someone, socialising with people and need to feel the information that's there, ads are going to clutter that up."
Brain Blau, an analyst at Gartner Research, added: "WhatsApp users have a really interesting profile, they are very engaged users who like to message in groups and those conversations are really what Facebook is after.
He said Facebook will at some point monetise WhatsApp users' profile in different ways.
"And as the user bases from Facebook and Whatsapp start to intermingle there will be an incremental revenue gain on the Facebook side as well," he said.
But while many users still value the service Facebook provides, says Blau, an increasing number of people are becoming aware about Facebook's privacy incursions.
"Today privacy is one of FB Achilles heels...There is always an umbrella over the users and they know that at some point that Facebook may use their personal information in ways they don't expect, and if Facebook isn't careful they could upset users if they dive too deep into their private lives," he said.
Woodward added: "They've taken a good thing and they need to keep it true to what it is...WhatsApp is doing really well on its own, particularly in Europe, which has become more concerned about privacy - it has given Facebook some penetration here.
"Now the question is how or will Facebook tweak it...they could tweak it too far and break it, which is what it's doing with its own privacy settings at the moment."