YEs, 4th ed is brutal IF the players are foolish, and the DM overplays the creatures, or, there is less than 4 PCs.
#1 Foolish players fight like 3rd ed. Or charge in etc. 4th ed is best played tactically. move and retreat, seek cover...help the tank by Area of Effect spells that burn down or weaken enemies around him once they are on him (AOEs that only hurt enemies are great), use abilities ot move the hell away, or knock enemies down...etc.
#2 Don't play monsters too smart unless it's appropriate. goblisn/orcs are simply tood umb to come up with great tactics, most of the time (orcs especially, goblisn can be sneaky)
see, many DMs are used to playing a computer game, or playing liek chess..but the NPCs are *individuals* they cannot see "the game board", or have telepathy with their allie s(well, not most creatures, lol).
This means they shouldn't be played with tactical perfection, except for really dealdy/smart foes, liek drow, devils, professional soldiers etc.
#3 when you have too few PCS, ie less than 4, to block strategic points, you can get "flanked and ganked". so it's good idea to run extra characters, when you have only 3 players or less.
