There are many reasons to install VMware ESX in text mode. The main reasons I use text mode are that it seems quicker for me and text mode responds better when using remote console connections, such as iLo, DRAC or console over IP. Previous versions of VMware used a text mode that incorporated Anaconda and was very similar to the text mode for RPM based Linux distributions. The new text mode in ESX 4 is VERY rudimentary when compared to the earlier versions. Hoever, it performs very well and is fairly straight forward to use.
The text mode installer uses simple lists of choices. Usually, 1 is for continue or to answer yes. Some items will have more than one choice. Here is a screenshot:
The console OS truly appears as a VM in this version. You must create a datastore and then a VMDK that represents the COS. A disk of sufficient size will be required for this. My first attempt, using an 8GB disk failed. My second attempt, using a 10GB disk was successful.
You can download a doc outlining text mode installation HERE.