Does it need to be compared to MGS to be considered good?
I think that it's completely counter-productive to do, MGS spawned a shift in the medium and a legacy that still holds up to this day, as much I love Syphon Filter (look at my profile pic) you can't just avoid to see the bigger picture here.
I've played both at release, and they are very different, someone pointed out that Tenchu existed too, Stealth / Action genre at his core revolves around the gameplay, it's legit to compare different games on this particular point, see their approach, new ideas, none got everything right between those 3.
The OST of the first SF is a banger, the danger bar system is cool, gameplay is fluid, the headshot indicator helps a lot, stealth section are good, weapons are varied characters are cool, hell everything is great to be honest, the main problem is making a comparaison with MGS.