is it worth upgrading a 2007 macbook pro?

Would like some opinions, insights etc. Macbook pro 2007, OSX 10.4.11, 2.16 GHz intel core duo, 667 MHz DDR2 SDRAM, 1.5GB memory

My I-pad was stolen this summer and not sure whether to replace it, upgrade this macbook, try to find the $$$$ for a refurb macbook, etc..

Doesn't want to upgrade so can't get apps now etc. Needs a battery (is off brand OK to buy?) or I use it plugged in. Any opinions would be valued . Thanks in advance.