I use a 7290 and I like it. With the amount of email I receive it is great to be able to deal with it whilst on the move and some spare time. It is great for composing emails. I never liked the predictive stuff and being to use a qwerty keyboard is much easier. The keys are small but satisfying when pressing them. It is very easy to use one handed.
I miss having a loudspeaker but that's about it. I never really used the camera on my other phones and many of the other features were redundant too.
I wouldn't use it for browsing PPRuNe as the pages are quite big and not designed for small browsers. I am hoping to eventually get the forums formatted for WAP which means mostly text based so that phone and PDA browsers can log on to them and make use of them.
THe Blackberry is slightly bigger than most mobile phones but I don't have a problem with that as it is quite slim and fits easily into a pocket.
Overall, I prefer it for getting email onthe spot and being able to deal with it easily. As a phone it is nothing special but the software has a great logic to it and is very easily used one handed.
I'd say go for it but don't expect to use it to browse PPRuNe until I've made a few changes.