If it does everything you want it to do at a price you think is fair, then it's good for you. That's a loaded question. What's good for you may not be good for me or someone else. Very subjective.
KEYBOARD -> that a actual keyboard with a sound module in. Very expensive, but the sounds are REALLY nice, if you look for the right one. And you gotta know if you want a sampler or a synthertizer... You can use them like a midi controller, but then, the awsome sounds wont be recorded. If you want the sound in your computer, you'll have to record them in the computer (and I'm not sure, but I dont think you can do that in Reason)
Suggestion: Yamaha Motif, Access Virus...
you could also look for the well known Korg Triton or
Midi Controller -> Since you're learning with Reason, that should be what you are looking for (in my opinion) with a midi controller, you can play all the plugins you have in Reason with the Controllerand it will be recorded directly in Reason.
Now what makes a good midi controller is the number of keys (depending on what you want, you can buy one with only 2 octaves or 55 notes or 88 notes) and the number of other controls on the keyboard.
Well may I recommend a keyboard? Check out da E MU PK-6. Its a great beginners keyboard and plus it has the knobs for tweakin and stuff. Check da link below for more info.