Pros

Set the alarm to music of your choice, including a 'shuffling' playlist - set multiple alarms - set volume and fade-in options as you wish - inexpensive - good customer support

Cons

Fade-in duration does not apply to snooze - yet!

Summary

I despise alarm clocks and have had a hate-hate relationship with them since I started using one. Loud and obnoxious, prone to not going off, easy to forget to set when one is particularly tired and simply falls into bed at the end of the day... Citrus fixes all these problems and more.
Lately, I've had an alarm clock that allows me to wake up to a CD. A small improvement over radio - I could at least ensure that I would not wake to obnoxious talk radio, static, or worst, bad music (if it makes me a bad person because waking up to Beyonce's snivelling "If I Were A Boy" starts me off in a foul mood, I can live with that). It did not, however, go far enough - even my own music was unpleasant when suddenly blared into a still, silent, peaceful room - and I am not someone who can wake up to a quiet alarm if played long enough. So when that alarm broke, I went looking for better.
I'd heard of fade-in alarms but was irritated by the lack of that option in all the store-bought clocks I looked at - not to mention the price they wanted when it was included. I also couldn't find anything that included both fade-in and the option to use your own music. One day it occurred to me that I was being very dense. If I was going to end up with something I didn't particularly want in the first place, I ought to be finding it for free - and where better than online? Yes! A free alarm clock, that's exactly what I should have done in the first place. And then I discovered that alarm clocks were not popular amongst the freeware crowd. I went through quite a few. They were frustratingly unreliable in their performance. One would work one day and fail the next three, another would have an alarm with the volume of an air raid siren that required six clicks to get it to SHUT UP already - I gave up, bought myself a cheap alarm clock, and resigned myself to a headache every morning.
I discovered Citrus purely by chance. It was shareware, not freeware, but ... well, it was only $13, and that was about half what I had spent on an alarm clock I hated - why not try it? I admit I went in prejudiced. I am not a fan of shareware - features are often limited to the point where you cannot tell without actually paying whether it's worth the price or not - and that is hardly the point. But Citrus does not follow that trend, offering a fully working copy to try for 30 days. Well within that 30 days I was already eyeing 'purchase'. The fade-in feature not only exists, but you can set the time to fade in. The option to choose your own music not only exists, but you can set it to work off of a 'shuffling' playlist and have your own music wake you up with a different tune every day! On top of that comes the ability to set multiple alarms by multiple criteria - so I can tell it to wake me every Monday, Thursday and Friday at 9am, Tuesday and Wednesday at 8:30am, and to bugger off and let me sleep Saturday and Sunday. Bliss! What's better, it has only failed to wake me up once - and that was because I had forgotten to set my new laptop to *not* automatically install Windows updates and shut down/restart. That is clearly the fault of Microsoft's godawful decision-making process - the designers of Citrus have gone as far as they can on their side by giving you the option, on install, of letting the program wake the computer from sleep mode so that you can keep your power-saver settings and still have peace of mind re: waking up on time in the morning. Once I'd told Windows what was what, I had no more problems with alarms not going off.
When the 30 day mark came, I willingly took out my credit card and paid the price - I also made a quick comment on the discussion board about what I liked about the program, why I'd bought it, and what I thought might be improvements. I was answered the same day about my suggestions, told that one feature I suggested was already planned for the next release which ought to be coming out 'soon', and actually pointed to where a feature was that I hadn't found yet. Browsing through the forums, I see plenty of other people having had the same experience, and lots of satisfied customers chiming in to give their thanks. So - good customer service, inexpensive software with no limitations on the trial version, a fully featured alarm clock that makes my mornings more peaceful and tranquil - hell yes, this was worth the $13. As for this being a 'scam' - I see no posts on the board about uninstallation problems (at least not more than one or two over several years!), no indication that one must pay for an 'uninstall' in order to get rid of it, and the only search results for "citrus alarm" + uninstall in Google's results are posts from Citrus's forums itself answering a request for help, and some extremely shady looking 'download our uninstall software now, we swear to god it's not full of spyware and other terrible things' websites. So... well, I'll remain a skeptic on that point for now.