Whatsapp's was sold for a jaw-dropping price, with more 0s than any normal people can count. I have no idea if this price is reasonable. As a user, I just want to talk about why I hate Whatsapp, as well as the entire class of mobile only proprietary messaging apps.
One immediate drawback for mobile messaging apps is that it is really hard to type on smartphone! Say all you can about how an on screen keyboard is as good as or better than physical keyboard. My experience is nothing like that. Correcting typo, which is happening all the time, is atrocious. It is very difficult to position the cursor back and fro precisely. Often it is better off to delete the whole word to correct a single mistake. Many times I simply give up and let readable typo, capitalization or punctuation error happen. My mobile efficiency is fairly low. On average I am able to compose about one to two messages per minute on a cellphone. Composing message longer than one sentence start to get awkward. For many people who carry a smartphone all the time but not necessary have access to a computer, the convenience outweigh the issues. But I am essentially in front of a computer all day. The inadequacy of mobile keyboard is obvious and really frustrating.
Another main reason I dislike Whatsapp is that it is a proprietary walled garden. I fundamentally distrust proprietary messaging network. If this were an open network running on standard protocol, someone would have create a desktop or webapp alternative to allow more access and fix the keyboard problem. Whatsapp decided they are a mobile only application. So we are stuck with whatever they made. They can decide on what they charge. And if the company fold one day or decided they do not want to provide the service anymore, you network will be gone with them.
The idea that Whatsapp will disappear in the short term seems ridiculous given its astronomical sales price. But I do not think its eventual decline will be far fetched. I have gone through a long list of once high flying instant messaging apps like ICQ, AOL, MSN, Yahoo messenger etc. People abandon them eventually. I have only recently disconnect from Yahoo Messenger. I left only after most of the people I used to chat with have long gone. By this time, majority of messages I receive from Yahoo Messenger are spam and porn. This is actually not an unusual end for these commercial networks.
For now I am an unwilling user, because many people, in particular of those in Hong Kong, use Whatsapp heavily. I bet with high confidence that within the next 10 years, some other app will come along and displace Whatspp. And I hope that this will be a message system base on open network.