A wonderful reference, I use it all the time. I find the lookup system incredibly easy to use - in fact, I haven't learnt how the 'skip' system works, I just seem to be able to find any character I want by 'following my nose' so it must be pretty intuitive.
The addition of stroke orders is useful, as well as highlighting important characters, which means this can be used not only as a dictionary, but as a casual browse. Also, I'm currently studying for the Kanji Aptitude Tests and the dictionary notes which Joyo grade each character belongs to, so I can easily make a decision whether to forget a looked-up character (for now), or note that I'll need it soon, or learn it properly.
A little light on compounds maybe, so combined with Spahn and Hadamitzky's "Kanji Learner's Dictionary" you get a formidable duo (although note that Spahn/Hadamitzky do _not_ agree on stroke order/count and radicals with the Japan Kanji Aptitude Testing Foundation - so use this one if you're learning Kanji for exams).