One of the real gems that I have found with Office 365 is Lync. I use it everyday and communicate with a range of people using it. I find it much better than Live Meeting and the only real downside I have found is that it currently doesn’t support the ability to record (see http://support.microsoft.com/kb/2433212/). My understanding is that it is only a matter of time before it does.
One of best things about Lync is that is now available on a variety of platforms, including those running iOS. However, not all the features of Lync are currently available on all platforms. The best way to find out what does and doesn’t work is to have a look at the Mobile Client Comparison Tables at:
So if you do have problems getting Lync to work have a look at the following articles:
Which are both great starting points.