I've upgraded version 1.3.4 and I have to stay it's the most stable version so far. 
1 2009-07-22 18:55
Re: PunBB 1.3.4 (30 replies, posted in News)
2 2009-07-22 18:51
Re: PunBB 1.3.3 (24 replies, posted in News)
bejo wrote:
hey,, succesly upgraded. But in 'another way'. these what i do :
i've backup the database, then upload the 1.3.3 version, but unfortunetly the config.php was deleted. so error happenend. Then i delete all the files, re unzip the 1.3.2, then instal, run db_update. then unzip 1.3.3 run db_update again. Voila, back to bussines again.
I've successfully upgraded using your method. It was very easy. Thank you