i was using bis for one gmail account and the gmail app for my other gmail account. i liked the look of the app but some of the formats on my daily emails (local news emailed daily) was unreadable cause of the app. plus i would have to restart the app every morning cause i have quick pull scheduled to do a pull while im sleeping. so i just use BIS for both accounts now.
i use gmail so much when im on the web, using the app made the most sense. i already have something like 4 or 5 different addresses going to it, and can add stars and such with no problem.
I like the Gmail app because I can close it and stop receiving emails any time I want. I can also search folders, including trash. It syncs nicely and just works.
I prefer using the the BB Messages center with Gmail getting pushed through BIS because I can do email, SMS, IM, Facebook, and more all from one central location. I have the Gmail app installed, but only use it when I need to search for an item older than is kept on the device.
Standard BB BIS email is faster, simple, and mostly better for me. Also works much better roaming internationally (significantly less data usage), or with a weak wifi connection. For some reason I never got fast push delivery with the Gmail app, also didn't like the gmail app spell check as much.
I open the gmail app occasionally to search for old emails, or find emails I sent from my desktop. Also don't have gmail 2 way sync for read / unread yet, so if I have been using my desktop email, I sometimes need to use the gmail app to easily find unread emails.
Gmail + Google Sync = Push. No excuse to say BIS is the better option. Gmail app does have some nice colors, though BIS e-mail obviously has much better integration with the rest of the system.
I use both. I have enough memory for both. The Gmail app is useful when you're not near a comp and want to search for an archived item, etc... I just keep it closed and use it when I need it.
Posted from my CrackBerry at wapforums.crackberry.com