Quite personally, I hate gambits.
My experience and stats so far playing the Danish gambit as white.

I like them because they lead to exciting games when accepted, as well as helping learn tactics. People always say "study tactics instead of openings", with gambits it's like doing both at the same time.

The danish gambit is pretty cool, I wouldn't be game enough to play it in a OTB game of more than 15 minutes though.
The problem with the Danish gambit is 2-fold:
1) Against black players who do not want to lose you have nothing against 3. .. d5 or 3. .. Qe7 (the position is roughly equal but personally i rather have black)
2) Against players who do want to win you are worse in the main line as is shown in the very nice piece from Pfren: http://www.chess.com/article/view/danish-cracker

Yesterday I got the book "Danish Dynamite" by Karsten Mueller and Martin Voigt, and found that the Danish is a much deeper opening than I ever imagined. I think that anyone who reads this book, plays through the lines on an analysis board, and absorbs all the information given within will have good chances to beat opponents even up to IM level, and this is exactly what I plan to do. There's a whole chapter devoted to declining with 3...d5, the so called Capablanca or Sorensen defense, which you say gives nothing for white, but in almost every position of the Danish gambit whether declined or accepted there are traps that black can fall into.
As for Pfren's article, I have read it and though I think it's a good article with good analysis, though I disagree with the overall conclusion.
After 5...Bb4+ white has a 67.6% winning percentage versus black's 23.5%.
http://www.365chess.com/opening.php?m=10&n=19781&ms=e4.e5.d4.exd4.c3.dxc3.Bc4.cxb2.Bxb2&ns=3.5.74.130.434.503.435.8792.19781
Even following Pfren's line up to the 8th move there are no wins for black in the 365chess database at least.
Furthermore Pfren's article hasn't gotten very much exposure and not many people are reading it. I've played 17 games now with the Danish here and I've not had someone go 5...Bb4+ more than once. And, even if someone does memorize the entire line Pfren gives, the Danish gambit isn't played very often, so will they be able to perfectly retain it in their memory when they're encountering it so infrequently? Do you think they have time for that when they're busy studying the Berlin Wall defense because they're expecting a Ruy Lopez?
The Danish gambit is also part of a family of gambits, it can transpose into a Scottish, Goring, or Urosev. All these related gambits have a synergy and by learning one you're increasing your ability to play the others. So let's say that a particular line becomes popular against the Danish and gives me problems, I can just switch to playing the Goring or the Scottish. But I don't expect that I will have to switch anytime soon, since I'm studying all the lines and positions of the Danish given by Karsten Mueller and Martin Voigt in their book, Voigt by the way plays the Danish even in standard time control tournaments and against GMs, and GM Karsten Mueller is a world renowned endgame expert so if anyone can tell how to win the endgames that can possibly arise in the Danish it's him.

Does early pawn sacrifice works 4 white agree he gets huge lead in lead in development but @ higher level would b difficult 2 get advantage after pawn sac....becoz opponent would equalise soon

Sounds great. I have experimented a little with the Danish gambit, but is nowhere near stable enough in it to play it OTB with standart time.
it would be cool to learn, but for some reason the book you refer to cost 150 pounds on Amazon!
That cant be right: http://www.amazon.co.uk/Danish-Dynamite-Karsten-Muller/dp/1888690208
Where did you get it?

I've seen the Amazon cost, which is highway robbery considering that this is trade paperback book that originally retailed for $19.95 and isn't even that old, being published in 2003. It's a very good book, but I don't think it's worth 150 pounds, especially considering it's sold secondhand and the authors won't get any profit from the sale.
Luckily I was able to find a copy in a used bookstore.
For anyone else looking for it, you can find almost any media for free online if you dig deep enough. I sent you a PM Lamberth.
There's also this book by John Lutes that was published in 1989. http://www.amazon.com/Danish-Gambit-W-John-Lutes/dp/0931462916
For those wanting free and readily available information, there's a really good video series on youtube by a kid calling himself "GM Tartarsauce". (His chess.com profile is here http://www.chess.com/members/view/Tsauce32)
http://www.youtube.com/watch?v=vD0xWNN1HQc
I've watched his series a few times and even took notes as I watched it. He says it was meant to be a seven part series but unfortunately he never finished the last two so there are only five. I sent him a friend request and PM on here asking when the last two would be released but he hasn't logged in since then.
Finally there's a Foxy Openings DVD on it by GM Nigel Davies. It's Foxy Opening DVD #21, and on ChessLecture.com there's also a lecture by IM Attila Turzo on the Danish, though the chesslecture video doesn't cover anything that's not covered in GM Tartarsauce's video.
About three weeks ago I decided to learn an opening for white against 1.e4 e5. Before this I had tried out the Ruy Lopez but thought it was too theoretical since I'm a new chess player and my 2..e5 opponents have probably been playing against the Ruy for years and have their chosen lines against it that they know a lot better than I do.
So I selected the Danish gambit partly because I knew my opponents wouldn't know it so well since it's not played that often, and partly in order to learn tactics and how to attack.
So far I've played 16 games with the Danish gambit as white. This is a gambit that seems to get declined a lot, much more than the Smith-Morra. Out of the 16 games I've had the gambit get declined in 9 of them. Here are my overall stats.
Danish gambit declined
6 wins 2 losses 1 draw
Danish gambit partially declined (second pawn not taken)
2 wins 1 loss
Danish gambit accepted
2 wins 2 losses
Overall I'd say the opening has been a great success, especially since I'm playing against people who are at least equal in rating to me. Also I haven't done much opening study of the gambit and don't know much theory about it yet.
I encourage all of you to try the Danish gambit and report your results back here as well.