At its highest quality, the 16-megabit-per-second mode, you can record almost 7 minutes of video per gigabyte of storage. That's about 55 minutes in the internal memory. If you drop to 9-megabit-per-second mode, that increases to about 10 minutes per gigabyte.
With the exception of the face detection, Smile Shutter, and scene modes, the camcorder has no bells or whistles to speak of. That's not necessarily a bad thing, but it could use a wind filter. The company dropped the NightShot infrared mode for this model; I doubt it was very popular, but I found it useful in emergencies. It forgoes Sony's usual 5.1-channel surround in favor of more typical 2-channel--no great loss there.
The CX100 incorporates Sony's 1/5-inch 2.4-megapixel Exmor ClearVid sensor, and the quality sensor really shows in the low-light shooting; though you probably wouldn't like the results from your latest pub crawl, video shot in your living room should look quite good thanks to the on-chip noise reduction. In other ways the video quality is typical of a lower-cost model. In bright sunlight there are frequently blown-out highlights, colors are attractive and saturated but some--like deep red roses--are off. The image stabilization works fine in tandem with the reasonably long 10x zoom lens. When viewed on a large-screen HDTV I noticed some smeary edges, though the video generally looks sharp enough. The lens focuses pretty quickly, but it could really use some better coatings; it displays serious lens flare from bright light coming in at oblique angles.
Given the widespread availability of better but larger older models from Sony and other manufacturers whose prices have dropped significantly, the real buying decision you make with the Sony Handycam HDR-CX100 is how much size matters to you. And even if you want it as small as possible, you should probably check out competitors like the Canon Vixia HF100 before committing.