It all depends on what you feel is important, and I do agree with many of the posts that state it is "your" decision. That being said...
My husband and I think it is deplorable to buy our kids more and more technology that serves NO truly viable purpose besides entertainment. My kids need no more excuses to stay inside sitting on their behinds playing a game...there are so many better, more productive things they can do with their time. Yes, you can learn a few things from a toy like a DSI...but you can learn those same things with a book, a constructive toy, or just playing or working with your child. Why would you ever promote less socialization, less creativity, and less physical effort to a child that young?
We have a 9 and a 6 year old who if we let them would spend 99% of their time gaming instead of enjoying themselves playing with other toys, sports, playing with friends, or even just being outside. The more technology access you give a child, and younger...the more likely they will become less physically fit, less social, and less able to amuse themselves without an "electric babysitter" (note the funny comment below about it being a great "shut-up tool"...which is fine for some people, but not the way I want to parent my kids).
I recommend checking out stores online like Creative Kidstuff or the Learning Store just to name a couple for some great gift ideas that will enhance your childs learning and growth, instead of providing them with an expensive way to occupy their time while providing no other benefit or function.
Either way...it is totally up to you, and what you and your husband enjoy and believe in...do what you think is best.