I think when it comes to purchasing phones or portable devices for the puropse of prolonged and lasting use its all about the treatment first and foremost and then the features.
As long as you treat them right, invest in maybe a silicon case or an invisibleSHIELD for it then wear and tear generally dictates that these devices last for a good number of years, I've had old 3310s and phones as such that go strong in this day and age.
Another thing to keep in mind are the features of the phone; for example you have many so called "top end" or "high end" phones on expensive plans that have a lot of features that may not be of much relevance (like 5MP cameras etc). On the other hand you also have a lot of new phones without the benchmark features (like 3G & Wi Fi) and this forces people to upgrade later down the line wanting to get new features.
The Bold, being a BlackBerry its a given that they will be feature-packed and as long as you know you will be using those features now and in years to come then there's no reason to get a phone with less/more features or upgrade before you graduate. I've never owned a BlackBerry myself and have been following the release of the Bold as it is the first BlackBerry that's caught my eye with ALL the features of a high-end phone and PDA so it could be the one I go for and from people I know, and the feedback I get on the forum, I can more or less vouch for their longevity in terms of wear and tear.
__________________ Blackberry Curve 8900