Pokemon HeartGold and SoulSilver are a revolutionary remake to the Pokemon series.
First of all I am still playing the game. I'm sure by the time it is all said and done I will have spent over 60 hours playing the game.
Anyways this game is great; especially for a Pokemon fan.
The Good-
Graphics: The graphics have greatly enhanced from passed pokemon versions. The characters, fields, towns, etc. have ALL enhanced. It is obviously a GREAT step from the original silver and gold. But it is also a step up from Diamond, Pearl, and Platinum.
Pokewalker: Some of you may have heard of the Pokewalker that comes along with the game. The Pokewalker, in my opinion, is one of the greatest devices that Nintendo/Gamefreak could have designed. With the Pokewalker you transfer one Pokemon from you storage box onto the walker. For every step you take you gain 1 Exp point. The down side is you can only level up once per walk. Another thing you can do on the Pokewalker is catch Pokemon. This is my favorite part. Using the Pokewalker I have caught (before the 3rd gym leader) Nidorans, Slopokes, and a Ponyta. Most of these Pokemon you find you won't encounter until later. Catching them is very easy to. The downside is is that when I caught them they were between level 5-10. However the more paths you unlock (I won't go into detail) the higher level the pokemon are you can catch. Another thing you can do with the Pokewalker is discover items which can be somewhat helpful. I have found revives and repels which sometimes can be helpful.
Other Positives: For those who have played Diamond and Pearl you will remember that you can migrate Pokemon. Soulsilver and Heartgold allow this ability to. Of course that is after you defeat the elite four and get the national Pokedex. The Wi-Fi ability is great to. Some aspects of the game you can enjoy with up to five friends. That depends on what you do though. But let me tell you, it is so cool.
The Bad-
In some ways it may seem repetitive but if you love Pokemon you will love it. Nothing, to me, is really all the bad. I mean you have to remember that it is a remake. So yes it may seem repetitive, it may seem re-done...but in the end it is a RE-MAKE.
Bottom Line-
I say buy the game. It is a great addition to the Pokemon series. When I play it it feels like I've never played silver and gold. I suggest %100 buy it. Its a great Pokemon adventure. :]