Both games are amazing, and the second has some of the best moments in gaming history!
It does indeed have some good moments but sadly they are sandwiched between 3 hour long boredom segments of brown.
Route kanal and Water hazard really stand out to me as areas that should have been entirely cut.
Then there is the weaponry, HL had a awesome selection of real and sci-fi weaponry which made every encounter immense fun, HL2? cut most of the awesome weapons for a few painfully generic items and the incredibly overused and tiresome mavity gun. The complete lack of fun weaponry is only made worse by the games length which makes you tired of them long before the half way point.
Ep's 1+2 are vastly better paced with far more interesting plot segments. The pacing was fast enough for you not to notice many re-used resources and the lack of new enemies/weapons etc.