I dont really think its that bad, its fun to play something based on the Half Life universe. The gameplay is lacking a lil refinement since its flash based. Controls are a pain though, you use your mouse to control the angle of your attacks and it gets tricky when you move Gordon pass your aiming reticle because hell well do a complete 180 if you arent careful leaving you wide open for attack. Notable things i liked are the inventory system just like the game which is cool,also they have a lot of sound effects taken from the original which adds to the atmosphere.
All in all not to bad for a free game, something to fill the void for anyone itching for more Half-Life.