I think it is. It has a camera, 당신 can buy games on wifi, and it has a lot of other cool features. I know that 당신 can't play Gameboy Advance games on it, but if 당신 have a Gameboy Advance, just use that. I know that the Action Replay for the regular DS doesnt work on the DSi, but they are coming out with a DSi ACtion Replay. I definitely think the DSi is worth buying.
If 당신 are considering buying a DSi and 당신 already own a DS, I would recommend waiting until 당신 are truly bored with your DS 또는 until it begins to...pass away...(break, stop working etc.) Then, when 당신 go to buy another one, consider the DSi.
If 당신 do not own a DS, I would compare the prices of the two thoroughly and then decide what 슈츠 당신 best. The DSi has it's advantages, but if 당신 just want the simple gaming experience, go with a regular DS.