well, let's put it this way. FW4 sucks but you don't have a choice but to use it =)
hehe seriously it works ok, but they dropped more than a couple of features comparing to the F100 FWs... it's only been 2 months though and we can expect some quality community patches soon I guess =)
Finaly, you don't really have to temper with the firmware unless you want to do something very specific, in which case you can ask here