Pokémon is as Marmite now as it's ever been, yet HeartGold and SoulSilver will still sell buckets. If you're a fan of the series you'll love it – it takes everything that's good about the franchise and gives it an extra sheen of quality. If you've never played one, do yourself a favour and give it a try – Pokémon is such a huge part of game history you should do it at least once.
It helps that it's actually a really enjoyable and quality game – you just need to leave your hang-ups that Pokémon is for kids at the door. Just promise that you will never be That Guy. You're so much better than that.