you see I had not noticed the bugs you mentioned, so I really would not want to suggest that you update in case the same mistakes happen (plus I have a 903, so things may work differently). The main advantages that I can see at the moment are the new filing system and the scrolling of pdfviewer. But since you use adobeviewer, and given that you can download and install the application for filing books separately, you may wait a little longer to see how the 2.1.1 works for people with a PB902, and in the meantime play around with the new application to see whether you like it.
I will keep testing, and report if I find any of the bugs you mention. For me the hirksome thing at the moment is not being able to change fonts in FBreader (and in coolreader, but as that one is developed for free, I surely am not going to complain - I am very grateful for all the work the techies of this forum do!).