I was expecting some marvelous increase in resolution since the file size goes from 7MB to 22MB. Do you guys see a big improvement?? Is RAW worth it?
RAW has nothing to do with resolution - the megapixel count doesn't change. RAW, unlike JPEG, contains all the information read from the camera sensor, and is not compressed with a lossy algorithm (one that discards data, JPEG does it). That's why sizes are so different. But not because of the pixel count.
Because RAW has more data (especially more levels - bits - for each color channel), it allows for recording more subtle transitions, and, when manipulated by a good application, there's more room not only for recovering bad exposed images, but also for improving good ones. Also RAW lets you to decide how to process the image, you know what you shoot and the desired final result. The in-camera RAW to JPEG converter (cameras always shoot RAW...) doesn't know, and applies a preset process.
Sharpening a RAW file with a good application may yield better results than in-camera sharpening, and deliver what will look better 'resolution', because finer details may be seen.
But mastering RAW processing takes time and requires experience. You need to train your eye to understand what kind of processing an image needs, and learn how to apply it with your tool(s) of choice.
If you didn't it already, look for books, tutorials, etc. to learn and understand RAW processing, a trial-and-error approach without solid foundations about digital image processing usually doesn't get you too far.