Platformers are still a popular genre of game even with the rise of hardware accelerated 3D gaming. However it can be a challenge getting one tuned so that it plays well and doesn’t frustrate the player so much that they end up looking for an alternative, or worse, take it out on their equipment (just do a search on YouTube for “gamer looses it” and you’ll find a few of these extreme cases).
With that in mind, and to save you falling in to some of the more common pitfalls, check out this article 11 Tips for Making A Fun Platformer.
The tips in this article are well worth making note of for future reference. It’ll make you look at Super Mario in a whole new light I can assure you :p