The SA-46 is a small, basic, 32-key keyboard. It's the little brother of the SA-76 (which is larger with 12 more keys but otherwise similar). It doesn't have a built-in record or sampling function. Nor does it have a keyboard split (where the left half of the keyboard can play one tone and the right half plays another). Come on Casio, it's 2013 ...some small keyboards in the 1980s had these features. On the plus side, it has 8-note polyphony - you can play up to 8 notes simultaneously. Most small keyboards in the 1980s had 4 or less.
It has 100 tones, 50 rhythms, and 10 built-in songs. You can adjust the tempo of the songs or rhythm. I often use the drum beats like a metronome while practising guitar. The big green piano/organ button quickly switches between those two tones rather than have to enter them manually. It's useful if you use those two tones a lot, otherwise it's a bit of a gimmick. It also has a very basic 5-button 'drum pad', but the buttons are stiff, which limits its usefulness. The small LCD display is non-illuminated.
The tones are listed in several categories rather than individually. I would prefer if each of the 100 tones was listed - even though the lettering would be small. The tones are decently natural-sounding, but still aren't as good as even the cheapest full-size keyboards from Casio or Yamaha. Some tones (such as the bass instruments) are actually quite good. The vast majority of tones are of real instruments, but there are some electronic and silly novelty sounds thrown in. If you hook it up to a good sound system, you'll find there is some surprisingly deep bass in the bass instruments and the drum beats. YouTube has some reviews & demos of the SA-46 if you want an idea of what it sounds like.
The 32 keys are small, but not tiny like on micro-sized keyboards. They have a springy feel which I don't like - I prefer a more natural 'thunk' feel - but you get used to it. The bottom half has strongly-rounded edges and is bright lime green. It has a carrying 'handle' indentation which is of limited usefulness. It uses 6 AA batteries.
This is a beginners' keyboard, so you have to have realistic expectations, but it's not a toy. As of 2013, Yamaha doesn't currently make any mini-sized keyboards. So as far as I know, this is one of the few (only?) inexpensive but decent-quality ones in this size. If you want more keys but in a somewhat larger package, there is the silver Casio SA-75 (a slightly older model that is still available), and the aforementioned SA-76.