A Boost i415 to relpace a Nextel i265?

My Nextel i265 doesn't work and I need a replacement.

All I need it for is to make and recieve calls, the walkie-talkie
feature and voice mail. I'm not interested in any 2 year deals or
anything like that. I'm looking at the Boost i415 as an inexpensive
replacement. Is this a good idea, and can I activate it by keeping my
regular Nextel service?

Thanks,
Phil