I've got a tugsten T3 and swear by it. Depends on what you want to do with it as to whether you need one.
I use mine for diary and typing up reports on the go - bought a keyboard to help with this.
Used to be a hairdresser, so guess you need a diary - excellent for this (but a lot of money just for a diary)
It has got docs to go which I use a lot - you might want to use a database to store all the client details, such as treatments etc. Hasnt got access but has got excel eqivanet which might be good to store all custmer details