I had that installed this week. Somehow it intercepts my voicemail and turns it into a text asking me to call a phone # to listen. I called Sprint as I thought it was a phone issue. Turns out to be Go. Does anyone else have that issue?
Under the settings in Handcent, make sure not to set Handcent as the default app, that's what's causing the voicemail issue. Be sure to go to the default messaging app and disable all notifications for it so you won't get two notifications for the same text.
You can still download handcent here:
Handcent sms HomePage --sms plus software for android
You can go there from your browser on your phone and have it downloaded directly to the phone.
And yes, Handcent has an option under the Notification settings to make a sound while you're on the phone when a text comes in.
I think it's a great app, wish they had a few more themes but it works very well. I used to use the pop up feature for messages, but they can still be a bit buggy and, when I have the phone mounted in my car in landscape mode, the screen doesn't always rotate to landscape so it's hard to read the message. Also, when a message does pop up in portrait mode, and I want to instantly reply, sometimes it takes some rather violent shaking of the phone to get it to rotate into landscape mode, it only does this though when I try to reply when the phone was locked. Going to the app and text from there and the rotate works just fine when the phone was unlocked.
Other than that it's a great program with some nice plug ins!