I've been to KL several different times during my gap year travels and have always found new things to love about the place. When I am weary of backpacking, being in KL is akin to taking a break and being at a city back home in the states. There are western style amenities for cheap prices, most people speak English, and the food is delicious. However, the city is also a reflection of the many cultural aspects of Malaysia, from the Hindu batu caves to china town at petaling street.
Insider Tip:As is true with traveling to any foreign place, it's supremely better to be shown around by a local. If possible, I'd recommend using a site like couchsurfing to find people willing to show you the things about their city you might miss if you went alone.