For those who don't want to renew your contract, this is a wonderful unlocked GSM phone with quite a lot of feature at a very reasonable price.
Before I get started, there is one point to keep in mind. This is an unlocked phone. There is some configuring that has to be done in order to get internet and MMS working with your provider. Nokia used to have a site that would send carrier specific info to the phone, but I believe they have taken it down. You may have to search forums and/or call your carrier customer support for this one. Call and SMS will work "out of box", but anything internet dependent will require some fiddling.
On to the review.
I have found for a $140 phone, this pretty much does everything I'd want a basic cell phone to do, almost to the point where I don't really care about have a higher end smart phone.
Call quality is great and I have found that the Series 40 UI far easier to use than most of the carrier locked phones we have in the UI. If you're using an ATT or TMO Nokia phone, you are not experiencing the full potential that Nokia has to offer.
Nokia's email client is great for basic email checking and even without 3G data capabilities, I found EDGE data speeds more than sufficient. With T9 predictive entry, even sending basic reply messages is relatively quick.
The media player keys are a handy touch, and the FM radio is also a nice additional feature. Overall, I found Nokia's generic media player much more pleasant than that of most other low end phones.
Onto some cons...
I have accidentally hung up on some calls as the screen tends to stick to my face and if I keep moving my hand, I will eventually slide the phone far enough to cause the call to end.
There is no feature to auto-lock the keys when the slider is closed. You either have to select the "Lock" option immediately after closing the slide or enable the auto keyguard feature to lock after a set amount of time. This is kind of a vestige of Nokia's candy bar only phone days.
No Nokia Maps. Even though this phone has no GPS, it's nice to still look up maps when you're in a bind. I've used several other S40 phones with this feature(with and without GPS) and although it's no Google Maps or Nokia Navigation, for such an inexpensive phone, it's good enough.
Overall, for the price, you will get a lot. If you're looking for a basic unlocked phone sans contract, this is the phone for you. You may even be pleasantly surprised.