I love my 9780, it is very fast, never lags or gets that loading clock screen thanks to the 512 MB of internal app memory. The photos taken with it are sweet and crisp!
The keyboard is very good, even better than the 9700, as they have made it in such a way that the keys are softer to press so that makes typing a little faster ( I have had both phones for a good while so I am not being biased), the build quality is amazing on both phones, they are very sturdy,
now........to the best part, they have the best BATTERY ever! All the BOLDs get the highest capacity battery so you can't beat that! 1450 mAh will get you flying for 1.5 - 2 days easily
You can't go wrong with the BOLD, just make sure you buy a screen protector and put it on before you remove the plastic off the screen as the screens are very sensitve, if you get ONE small scratch, when viewing anything on a white background like a website for example, that small scratch will look like a rainbow line :( so be warned, you MUST put a screen protector
And please dont go for the privacy protectors as they plain make the screen look ugly and dark! losing its shine and purpose of getting a BOLD, just get a regular transparent screen protector