From the Lightview project site:

• Clean: Designed to compliment your images.
• Fast: Images and their neighbours are preloaded.
• Easy to customize: You don’t even have to know CSS.
• Rounded: Adjustable rounded corners, without PNGs.
• Smart resizing: Images will always fit on your screen.
• Slideshow: One button slideshow.
• Effects: Using Scriptaculous.
• Works on all modern browsers

Lightview is similar to Lightbox 2 and both are built with Prototype and Scriptaculous. However, there are a few differences I noticed:

• The morphing effect that Lightview uses is a refreshing change (probably because I have seen the Lightbox effects too many times!).
• Lightview allows you to customise many of the visual aspects of the viewer programatically. For example, the background colour and corner radius.
• Lightview supports a customisable slideshow option which Lightbox lacks.
• Lightview uses the caption attribute of the <a> tag to give images a caption. This attribute is not valid XHTML and thus its usage will produce invalid markup. I would suggest using a convention similar to that used by MooTools Tips: title="image title :: caption"
• Lightbox has been around for a while and is well tested and proven.

Personally I like the look of Lightview but I wouldn’t use it because I don’t like invalid markup!

If you are interested in something similar for the MooTools framework, try Slimbox.