I just installed OZ 3.5.4 Opie image on my 5500 and liked it very much.
I found a couple of issues tough:
1) I attached a SanDisk 802.11b Low power card, and while it is recognized and I can configure it with the network tool, I have serious stability issues with my home WiFi connection using a 128bit WEP encription. The card connects but loses the link after a short period (I can barely update the feed list!) and I have to extract it, suspend and resume and reinsert it to have the connection back for a short while
2) My SD card is recognized and I can use it, but it is not shown in the card applet in the panel
3) Apparently the automatic time update is a bit erratic as it seems not to consider the timezone and sometimes it completely changes the time
4) Sometimes it freezes, especially with the CF card inserted
I hope this issues can be easily solved because I like the new rom a lot! :-)
PS: speaking of small old bugs never corrected, apparently the console can still not be closed using the exit command, as in the good old 3.1 times! ;-)