Hi Tom,
I used Quattro a few generations ago. It's original design intentially used Lotus 1-2-3 commands, making it very easy for 1-2-3 users to switch over to Quattro. Lotus screamed foul at the time, but I don't think they were actually able to force Quattro into changing anything.
My boss at work uses Quattro for Windows and refuses to move to Excel, mainly because it is much easier to create and modify graphs in Quattro. So, play with it a little. Though it has been awhile since I used Quattro, my experience was that it was fully compatible with Lotus and easier than Excel.
It has lost a lot of popularity since Excel arrived on the scene, so I wouldn't want to guess how long quattro will sirvive. Perhaps its use is much more widespread than I imagine.
Lou