If it's a 2009 plastic unibody MacBook or higher (basically, anything with no buttons on the trackpad), it'll be excellent for your needs.
With an SSD they browse the Internet really smoothly. In tandem with support for 10.11 and the trackpad gestures, I would choose it in a heartbeat over any new Windows laptop at that same price.
Conversely if you get one of the slightly older MacBooks which have the one-button mouse, it's the exact opposite. Ancient OS support, crummy trackpad, limited RAM and awful GPU (even for the time). They're two completely different machines.
To conclude: old MacBooks with an SSD and maxed RAM are still fab, but avoid any which have a physical button below the trackpad. They can look very similar in listing photos so be careful and triple check here if you're unsure.