Nothing wrong with a Comet in relatively sheltered waters and fairly light to moderate winds, at least to learn on. It's an old design, fairly lightweight, flat-bottomed, with a large mainsail and a good amount of sail area for its weight. Translation: for an old design, it's pretty fast and responsive, but you could get overpowered when the wind gets over 15 knots until you get more experience, hike out to windward, learn how to luff and "feather" into the wind to keep the boat on its feet.
The good part: it's a responsive, nice-sailing boat which, in around 10 knots of breeze, would be a delight to learn on.
But it's hard to reduce sail if it breezes up, don't think you can reef the main, you'd drop it and sail in with the
jib I guess, as long as you weren't trying to get to windward. It's a racing boat from the 40's, centerboard not keel, so a bit faster and less forgiving than the lower-performance boats. Not self-bailing either, so if you capsized you'd fill up and need assistance.
Follow your heart--if you love the boat (not that many wood boats left these days) and pick your weather and sea conditions, you can learn to sail just fine.
I'm assuming hull and sails (dacron, you hope, not antique cotton) are in decent shape despite the low price.