It doesn't beat the original, but it comes pretty damn close.
While many areas are repetitive and the "box behind a door so you can't open it" ways of making it totally linear are getting kind of old, I still like them. Personally I can't stand shooters where you have to spend 10 minutes just to figure out where you're supposed to go next, here you can pace yourself because you'll never get lost - the next firefight happens when you want it to, just walk into the next room, you don't have to go looking for it.
Next comes a bit of a spoiler, but I thought the abandoned train station and the metro station firefights were some of the best in the series. The graphics are looking a little bit dated and the "boxes everywhere" design has been a problem of the series, but it works out pretty nicely for people who don't have $2000 to upgrade their PC every year - they can still run with max settings on older machines.
All in all, this makes a pretty decent expansion, an alternate insight from a simple team of soldiers into a story beyond their comprehension.
"We have another survivor in the building, a little girl, about 8 years old"
"-What the hell are you talking about?"
"-She was just there!"
That's when you know you're f****d.