As Kuala Lumpur is a city, I don't think people who are into sightseeing should be there. It is a nice place for a short getaway with local food and some nice cafes. In addition, it is also quite similar to Singapore, which is a multi racial, multi cultural and multi religious city. If a longer getaway is planned, may want to consider getting out of KL to visit the surrounding places of Malaysia.
Insider Tip:Stay in Back Home Hostel, and experience their city tour. It will not disappoint.