BlackBerry OS 4.6 through 5.0 application behaviours I really dislike:
RIM is apparently hasn't fixed the two main complaints about OS 4.6 in OS 5.0, so it bear worth reposting again. I post here not in Beta-you-than-me, because it covers nitpicks found in OS 4.6.
(I am using 5.0.0.238 right now)

#1: BBM 5.0 is wonderful, and I like it for the most part with one exception: I want a more compact display for the buddy list! Please add an "old school" option to all the fancy instant messaging applications including BlackBerry Messenger, MSN, AIM, ICQ, Yahoo, Google Talk:
[X] Use Compact 1 Line Display (instead of 2 Lines Display)
[X] Use Compact Title Bar
Or even simply:
[X] Use Compact Display (1 Line for Title and Buddies)
Some of us do not like the wasted screen space of the new instant messengers; it is wonderful for many of us, but some computer geeks really prefer the old-school instant messaging look (some of who are the ones that persuades friends to buy BlackBerries, you need to keep old-school BlackBerry geeks happy so they keep recommending BlackBerry to new users). Please, add options to all your instant messengers to be able to make them look more old-school.

#2: RIM needs to standardize zooming feature on non-touchscreen devices. Standardized hotkeys. Standardize on the letters "i" and "o" for zoom in/zoom out in all photo apps and web browser apps, because I really really really want to zoom in/out more easily in a more consistent manner in all BlackBerry applications. iPhone has pinch-zoom, but the very least RIM could do is to standardize zoom hotkeys
"i" == "Zoom In"
"o" == "Zoom Out"
Which has always been the case for the web browser but RIM does not consistently implement these in all applications that use zooming features, only some of them. And they actually removed these zoom hotkeys from one of the apps!

Yes, there are other nitpicks, other bugs, just the above have been recurring inconsistency trends for the last 1-2 years that I would like to see reversed, with easy bugfixes -- these aren't OS rewrites after all.