The graphics in The Last Revelation are a definite improvement. A new skinning system means no more disconnected elbows, and better shading for the characters. The improved lighting effects are a wonderful new touch, letting sunlight stream in through cracks. Surface mapping makes textures look more realistic, while bump mapping is also there to give a sense of depth. One other neat feature is the water which drips off of Lara after she gets done swimming.
Enemies are varied in The Last Revelation.
There are a few animals that come after Lara, though most of her opponents are undead inhabitants like skeletons and zombies. More vehicles are also in The Last Revelation, so be prepared to chase down the bad guys a few times as well. Improved enemy AI means it's not always easy to find a safe spot to shoot away at the baddies. If it's possible, they will try and leap their way towards Lara with improved path-finding skills. The journal is another nice idea that has been implemented in The Last Revelation.