I am using the Nokia N 70 for quite sometime now. Never had any problem with that. Have tried using 15 applications at a time. It works exactly like a PDA. You can not only listen to music & call at the same time but can also use the games with sounds turned off. I have used the office application (word, a pdf file, a power point presentation & an excel sheet) with the applications used above. i.e, I was active on a Call & music, games, powerpoint, pdf, excel sheet, yahoo go, word document were open in background.
The only improvement what I wanted by the phone is to support is Wi-Fi & also it would have been nice if the phone was capable of handling a memory card more than 2 Gb or like N91 if it comes with a 4 Gb buit in memory then it would be great. And also the main camera should be made a button operatable rather than the slide door.