Hiya,
Winback at first seemed like a Metal Gear Solid ripoff, in a way. There's still a story, and it functions pretty well... (the story, that is).
The game wasn't too enticing to start off with... and it may seem a bit 'bland' at times (probably because of the music, which can be cool too), but perhaps that's not the right word. It's not bland. There're some really good points to the game.
I've played it on both the N64 and PS2, and it's a great port from one to the other. PS2 has more options and stuff for multiplayer, so that's cool. (Did N64 even have multiplayer? I forget... I think so). I don't know how multiplayer is, to be honest, but I'd assume that it's mostly strategy, working with your partner. I'd say there's a BIG section of average players that could compete with each other, but only the elite come out on top consistently. Think Goldeneye in terms of skill level -- anyone can be decent and be considered 'Good', but the best are just that -- the best.
Don't get me wrong, just cause it's 'multiplayer' doesn't mean you can't play it single player (I think). At least, there are 'challenge' missions to keep you occupied. There's a good amount of variety in those, and they can get to be very hard.
One major complaint I had at first (not a big deal) was the speed at which the people move. A lot of times I was like, "HURRY UP AND MOVE FASTER YOU LOSER", but it's not so much that he was slow... I was just kinda tense. This game makes you tense and gives you sweaty hands, not knowing which way a lot of battles will turn.
99.9% of fighting are gunbattles. If you're in that 0.1% of non-gunbattles, you've probably been knocked to the floor by the bad guy. You'll probably get up and shoot him in the face. The game's fighting revolves around 2 techniques -- wall hugging, and rolling. Sure, you can run in the open, stop, and shoot, but it's MUCH safer to stay against a wall, pop out, lock, shoot him a few times (or once in the head, if you can flick the analog up real quick... an excellent skill you'll be proud of), and hide behind the wall again. The wall hugging/shooting is key, and is thus developed very well by the game designers. Rolling is the other key technique. You'll use it ALL the time, believe me... and a lot of times, it'll be diving for cover... and you wonder, "Will I get shot? Will a bullet from that lady's machine gun clip me in the foot and kill me?" Again, tension.
Time flies when you become engrossed in this game. It may be that you're just trying to beat a certain boss (infinite continues. You'll NEED them). There are a lot of bosses, which increases the variety of this game... which is probably one of the BEST DESIGN ASPECTS of this game. Yes, there will be times when you'll have to go back to get something or do something. That's okay, because you need the practice in killing and stuff... and you don't mind killing, because it never gets boring (not like some repetitive RPGs). However, the variety mostly comes when you have to move forward... there's a LOT of times when you'll have to do so... and there'll always be enemies in new places. I don't think I've ever been caught in a pincer attack (enemies on both sides), so you don't really have to worry about that. Wall hugging is almost always a guaranteed safety... almost...
I won't be spoiling anything by saying this, really, but let me tell you..... people die... and I've put at least 20 hours into this game.. or was it 10... and I STILL haven't met up with all the characters. Need story? Here's how it goes, from what I recall.
Jean Luc is appointed head of some covert ops group. He's a young guy, but has the best shooting scores or whatever... and that's who you are. So you and your group of coverts (I don't know how many are in the group... a handful, though) are sent to infiltrate an area where terrorists have threatened to something something missiles something something. You don't all travel together... but you will meet up with them from time to time. Wouldn't be surprised if there were traitors... not sure though.
One last note... back to the bosses... I don't remember them all, but I DO remember something about a woman with a machine gun (you're lucky if you still have the rocket launcher. You don't get it often)... and the COOLEST boss I remember is the one with grenades. He had a gun, too, in case you felt it was safe to poke your head out from behind the wall, but he chucked grenades that still could hurt you (depending) even if you were behind a pillar... so you can't hide there forever.

Even after you killed him, he advanced the story. Not bad, huh?
For $10? Heck yeah... I won't get it, cause I'm not buying games right now... but heck yeah... it'd be worth it. There're plenty of hours of gameplay in it... I don't know what happens if you beat it (I rented for N64 once... played for quite a while, bro had it for PS2 but he took it with him, and I just got a PS2)... you know, codes or difficulties or whatever, but I'm sure you'll leave the game satisfied. Especially for $10... and I've heard that the Castlevania games have started to decline in quality over the years... this may be worth it, eh?
Hope you take this offer! Let me know how it's turned out for you!
~Kap