So far I've seen two levels and it was mostly secrets/puzzles, with little fighting.
Is all the game like this - a lot of puzzles, or it become combat/tactical dominated later?
As Crypt is the very first area you have to expect some warming up first. I can guarantee that the next area of Swamp, while very puzzle-y too, is more tactical otherwise you become flooded in undead. Same with Slaver's ship and further. The puzzles will always be present to some degree but majority of them are quite easy to finish.