additional controllers

Why on God's green earth in this digital age any company would ship an item like this without an AC adapter when they come standard with $10 items is beyond me, but sure enough, it doesn't include one. To top it off, it doesn't even tell you what kind to buy - it tells you to get some obscure coding that the guy at Radio Shack had never even heard of.

Outside of that, which really warrants a rating of 1 star, it is really really cool! My fiance loved it! Definitely a lot of value for the price. Looks like she'll have endless hours of fun with this thing, and it teaches you! Amazing! Lighted keys? Will the madness never end?

This does exactly what it says it will do, has great sound, easy to set up and get started, lots of tones and other options. Overall great product but let me add a few things I wished were different.

More rhythms

Keyboard does not save last tone when you turn it off ( you may be able to do this but I have yet to figure it out)

Many of the songs included are lame

Casio includes a service where you can download more songs but they have like 50 songs there and it seems like a web site that they may have forgotten about since many of the "coming soon" dates are from 2000 and 2001. Also, you cant download the songs directly to your keyboard they remain on your PC.

If these features are not important to you then this is a great buy.

In my mid-30's I decided it was time to finally learn to play an instrument - and the Casio LK55 fit the bill (my husband requested I pick an instrument that could be used with headphones!).
The keyboard has realistic sounding instruments, and a pleasant piano sound. Keys are full sized, and the lcd display is very useful once you figure out what the general functions are.
It has a good range of built in songs that you can play along with - I found as a beginner that most were too complicated but I'm working on it.
I've actually found that I don't use the key lighting as much as expected. Don't expect this keyboard to 'teach' you how to play. You really need to purchase some good instructional materials and learn the old fashioned way (lots of practice!) but it is fun and gratifying to play along with the built in songs in-between regular practice. My only complaint is that if you want to learn a built in song using the key lighting - you can't learn both hands at the same time. You learn the right and left hands seperately - which I can understand as the lighting might be confusing otherwise, but it would be nice to have the option.
I'm extremely pleased with the keyboard, but it will take a while before I'm competent.
I highly recommend the book "Adult All-In-One Course: Lesson-Theory-Technic" by Willard A. Palmer. It's been extremely useful for learning the basics (such as How To Read Music!).

Pluses:
1. Portable (can use batteries or power)
2. Key lighting is great
3. Large selection of built in songs
4. Full size keys
5. Can connect to computer

Minuses:
1. Can't magically transform me into a concert pianist
2. Headphone jack is at the rear of the keyboard & is awkward to access
3. Can't learn both hands simultaneously