The reason I use Google Voice as my Voicemail client is because they offer voice to text conversion of voicemails. Additionally, you can check your voicemail online. With Ting, you can only check voicemail from your phone or from another phone.
I guess maybe it would be cool if Ting allowed you to listen to your voicemails from their webpage when you login to your dashboard/account in addition to being able to check your voicemail via phone. For such a techy company, this would be good feature to boast.
It would be great if you also offered voice to text conversion of voicemail, but for the time being, a simple way to check and listen your voicemail from a computer would be ideal.