How does TR1 work for you?

On my pentium 4 2.6Ghz and FX5600 TR1 1GB of Ram with Dosbox, the game doesn't want to run properly. I had to turn off everything, including virus scanner so i can get smooth 24 FPS
So fortunately I can play it.

Did the training mission in lara's place and did few minutes of first cave. To the place where you can shoot bear from the top of the bridge.

Few thoughts:
Graphics are pretty bad. Quite a lot of artifacts, texture bend in weird way. Also having trouble with depth perception. Hit the wall even tough I thought it was a corridor. I think I'll get used to that.
Controls are wonky :) all keyboard, using ctrl, delete, page down and 'zero' on numerical pad... haven't done that in a long time. Muscle cramps are a certainty.

Few questions:
Is the game linear or quite open? It being from 96 I presume its more open than linear. but can you get lost, miss something 12 miles away?
is it generally hard (the puzzles and combat. controls i'll learn)?
Any suggestions you can give to a player who never ever played any of TR games?

edit: I also loled at lara's clothes and first scene. she is on top of a mountain, everything is covered in snow yet she is wearing a tshirt and shorts. I always assumed that she raids Egyptian or south American at a sea level tombs not high up on the mountain.
and the first scene where the guide just dies and she leaves his corpses behind? her heart must be colder than the snow around her.