IMO vs TeleMessage

Although IMO has a comparable, and in some cases superior, feature set when compared to the competition its key selling point is its interface.

From LifeHacker when it won "Best IM Client":

Signing on, navigating chats by tapping the tabs at the bottom, searching for buddies, and virtually any other operation is easy to find and use. The app, itself, is very quick. Even sending a voice IM, if you don't feel like typing, is responsive and sends quickly. Everything imo does it does well, but it's excellent navigation really makes it top notch.

IMO also has a fully functional website that you can use for chat while on your desktop or laptop. This really puts IMO ahead of the competition as you can use the same system on all your devices so you don't have to deal with overlapping notifications etc. (Note: IM+ also has this feature)

It should also be noted that it has the highest rating in the App Store due to both the UI and its stability.

Tabbed chats make it easy to switch between conversations

Both your buddy lists and chat histories are searchable.

Concurrent sessions allow you to be logged in on your desktop while also being logged in on your phone.

They've been in the messaging business for over 15 years. Not a start-up, and use carrier-grade infrastructure.

They offer a bunch of APIs that you can integrate with own apps to automate messaging.

While the solution includes an app, messages can also be sent from a computer or Outlook. It can send data messages, text messages, voice messages, etc (as long as there are enough message credits).

An organization's mobile messaging can be managed by an administrator. That means admins can add, delete or suspend users and enforce messaging policies.

TeleMessage uses end-to-end encryption, with an additional encryption layer while data is in transit. It also offers a bunch of other security features such as PIN lock, time limited messaging and forward locking.