I believe and understand there was a lot of software problems with the original Blackberry phones which have now been resolved.However many people wait until good reviews are issued to make up their minds, then it is often too late as another more up to date issue is available.
As a pda I suppose they can not really be beaten, but only usefull if you have the software, and the requirements to use them.
They can be good to use for keeping notes, and connecting to the internet to acess files and retrieve information about a client whilst your in the field.
If you need a phone that rings when you are called, and calls out, then no, the blackberry is not for you.