Well, we've been and I loved it all. Got bus from airport to centre - easy and very cheap. Stayed at the Astoria hotel - very central, clean and we had a great room with a roof terrace and view of the castle (paid for upgrade). Breakfast excellent. Great meal at Pasta Fresca and street food totally yum. Prices vary a lot - beer can be 30-100 koruna - castle side of the bridge far cheaper to eat & drink. Jazz club in centre cheap & fun. Castle highly recommended - you can spread your trip over 2 consecutive days - we didn't but wished we had as there was so much to see. You can also walk up to Petrin Park for amazing free views of the city. Have put quite a few reviews on Trip Advisor back at the end of Feb.
We ate at a lovely restaurant, near Mala Strana, it was something to do with Maltese Knights! My parents found it again a few years ago, and said it was still good. I've done a quick Google, and I think it's still there with good trip advisor reviews.