FPGA are fun to work with ... when the tools work. New versions of the tools come out, then serice packs, but there is no light that the tools would actually work better. This is towards Xilinx tools. I used lately also Quartus 4.2 for several desings and dont recall having any tool related issues at all.
there are some my current identified problems with ISE 7.1, unfortunatly backing up to 6.3 doesnt also work for me as the most needed feature has a problem on 6.3 - chipscope core inserter makes the working design a non working design.
I can not belive that everything do try todo with Xilinx tools is so weird that nobody else (e.g. xilinx internal testing team) has ever tried that. But with almost anything I touch I see the tools either crash or not properly working.
Some issues are minor, and I can figure out some workarounds, that takes time, but if the problem can be circumvented its ok. Some issues are more fatal. At the moment the current state (of xilinx tools) really doesnt look like the next service pack would resolve the major issues (those I am aware of, there are mort likely many more of them).
At the very present moment I am really in not good mood as I need to verify some designs VERY URGENTLY and the tools just fail there where I need them.