I just bought it and crap all mighty is it hard! I only gave it a quick try, but I have a feeling I'll be spending a lot of time with this game.

I beat this game multiple times when I was a kid. It's hard, but not to hard. Mario Sunshine was harder.

This is a bit harder than the Mario all stars edition, that was made a bit simple so it could be beaten easier.
This one in my opinion is harder, so if you have played the all stars edition, don't think youve beaten this edition.

 SMB All Stars was gimped. Different physics. No wind. Gimped. Gimped. Gimped.

Um, The Lost Levels in Mario All-Stars most definitely had wind. I eventually finished D-4 on it years ago and completed the game.

Yeah, I played it on the SNES as well. It might have been because I was just a kid, but back then I thought the game was hilariously fun.

The game is hard, but I don't recall its hardest levels being any tougher than the toughest SMW/SM3 levels. Its just that there are about 20-30 really hard levels in lost level but only half a dozen or so in SMW/SM3. On all-stars it wasn't too hard to grind through cause you could save on any stage and get 99 lives using a trick on the first level. If I remember correctly I beat through stage D over a few days of intense gaming.

I can't imagine how frustrating the original must have been, assuming you couldn't save at all.

Shame it was only a times VC game, I missed out because it's down now, luckily it came on the SNES.

It was a limited release in Europe (and I don't understand why), but it just released in North America this week, along with Sin and Punishment for the N64, with no announcement that they would only be available for a limited time.