I just beat it after playing it on and off for about a couple weeks. This is, hands down, one of my favorite games of the month, the year, and hell, it beat Dark Souls as my most enjoyed game I bought from Steam. I'm just gonna copypaste my opinion I told to a friend the moment I beat it:
I had a ton of fun with Strider. It's almost one of my most favorite games of all time, but I don't know what makes it not quite up there with favorites like Metroid Prime and Super Mario World. It's got some of the tightest design I've seen in years and the action is fast paced and fun. Looking around all over the map provided hours of entertainment in itself, and the story leading you a linear trek before that was hilariously bad. The game almost praises me as well, with some enemies sounding like they said 'Mayo is god'. There's a lot of freedom even when the game is at its most linear, you can climb anything if you put your mind to it, Metroid-style enemy freezing allows you to use them as platforms and the warp dash maneuver is one of the coolest powerups I've ever seen. I guess my only complaint is the weapon switching can ♥♥♥♥ you over if you're using a 360 controller and it's abysmal D-pad and you can't turn the hint system off. I've been plenty challenged and I've only beat it in Easy Mode. There's still a lot to learn too, as I've seen a speedrun of it that took advantage of clipping glitches and half way through there were so many glitches stacked up I couldn't comprehend what was going on. Sadly, I don't see any chance of Strider returning anytime soon, as the marketing for the game is basically non-existant, and even then, Metroidvanias of this quality are very rare and precious. It's still my GOTY.
So yeah, buy this ♥♥♥♥ing game if you love 2D action titles of any kind. It doesn't ♥♥♥♥ around with needless story and exposition, you don't need to care about anything except that you're a ninja who kills cyborg Russians. It's part maniac hack 'n slash and a metroidvania if you spend more time into it, and if any of this raised your eyebrows, you wasted too much time not playing Strider.