The first Tomb Raider was a classic in terms of its 3D gameplay, sense of exploration through massive levels, and a unique main character.  The 2nd installment in the TR series is not much different.  The levels are still HUGE, and exploration is still the name of the game.  But this time around, the environments and enemies are more varied, there are more action-based enemy sequences than the first, and the difficulty level has been approriately increased.  In terms of the level of challenge, I feel that this is the best in the series.  The later Tomb Raider series felt frustrating and downright cheap at times.  This one is definitely not a cakewalk, but is very possible without a strategy guide.  You don't feel as though you have to play for half an hour just to get into the next room.  Progress is slow, but steady, and you don't ever need 6 or 7 different items to move on.  Progress is more based on actually getting where you want to go rather than finding the right items or hitting the right combination of switches.  Some of the level designs are incredible, such as the Venice-based levels, the Opera House, the beastly Barkhang Monestary and the massive Temple Of Xian.  This is the key strength of the first two TR installments, and why the more recent ones have been less inspiring.  Resourcefulness and attention to the environment is extremely key, as medipacks are in light supply in this game.  Also, every level has 3 secrets in the form of dragons.  You do not receive the bonus items unless you find all 3 dragons in the level, making exploration even more vital in building your inventory.  Finding at least 2 of the dragons in every level should be quite easy, but some levels have one especially well-hidden dragon.  The gold dragons in the first two levels are remarkably difficult, but the reward of finding them (especially the first one) is worth it.  If you didn't like the first Tomb Raider, this game won't change your mind.  If you were blown away by the first installment (or even the 3rd, 4th or 5th) then this game is a real treat.