If you're a fan of the original, RayStorm HD is well worth looking into, even if the $15 price tag is a little steep.
http://www.gamespot.com/ps/action/raystorm/index.html
Others have already pointed out GameSpot's extreme reversal of their opinion with the release of RayStorm HD, so I won't go into it any further here. Instead, I'm writing this as a recommendation to those who have already enjoyed the game in the past.
In my case, RayStorm was the third PlayStation game I owned back in 1998, and I've been a huge fan of it ever since. I'd randomly thought for a couple years now than an Xbox Live Arcade release would be nice, but I didn't think anyone cared enough about the game for it to ever happen. Imagine my surprise when I stumbled across it's existence by chance a few weeks ago...
Having had a chance to play it quite a bit lately, I'm pretty much thrilled with it. The game looks wonderful in the updated HD graphics, and still manages to stay very true to the original. Nearly every detail about how the game plays was transferred perfectly, and much to my surprise, it actually handles very nicely with the 360's d-pad (which I'm ordinarily not a fan of). While some have said the new graphics cause far off ships and missiles to be harder to see, I actually find that I can see things more clearly in this version than the original.
All the music and sound effects were transferred exactly from the original, and while some may criticize this, I personally am quite happy with it. At first I was kind of wishing they had updated the explosion sounds a bit to go with the new graphics, but after playing it more extensively, I'm glad they kept all the sound identical to the original. It seems to retain more of it's charm that way, and the original game's sound quality was quite impressive for it's time to begin with.
Aside from the graphics, they haven't changed much or added anything significantly new, but the subtle tweaks they have added are a nice touch. The R-Gray 0 prototype ship is now unlockable to use in the regular modes, not just 13 Ships Mode. In the original RayStorm it was essentially a recolored R-Gray 1 without the spread shot, Hyper Laser, or Special Attack. Here it is mostly similar, but this time around it can move a bit faster than the R-Gray 1 or 2, giving it a slight advantage to compensate for the reduced firepower. They've also tweaked it's appearance to make it look more like one would expect a prototype of the R-Gray 1 to look. It's lasers and primary shot are now red instead of green, it's main rear thrusters are more rounded and dated looking, and the sound of it's computer system (lock-ons and power ups) and lasers sound more like one might expect an older prototype version of the R-Gray 1's systems to sound. Outside of the speed difference, none of this has any real affect on gameplay, but it's just a nice touch.
They've also added a new ship, which interestingly shares it's name with the canceled RayForce sequel, R-Gear. The R-Gear plays considerably differently from any of the R-Grays, although it bears very slight similarity to the WR-3 from RayCrisis. In addition to increased speed, it's primary shot is a stream of heat-seeking missiles, while it's lock-on system uses an energy bar instead of the limited 8 or 16 lock-on system of the R-Grays. When you press the laser button, your targeting system becomes active and the laser canons disengage from the ship and hover nearby, shifting position closer to your targets as they fire. They fire automatically as you lock on, and will continue doing so until you disengage the system or the energy bar runs out. The bar recharges within a few seconds of disengaging the system. The usual green powerups that would increase your lock-on limit with the R-Grays will increase the size of the energy bar, allowing longer periods of sustained targeting. The R-Gear's special attack further increases your speed, makes you invincible, and gives you unlimited energy for your targeting laser for a short period of time. Overall it takes some getting used to, but it's an interesting change of pace.
I only have a couple minor complaints with this version. I wished it would have included the ability to change ship colors, as I used to always plug into port 2 and play as the blue ship in single player games on the PlayStation version, but that's not a big deal. I also think $15 is a bit steep for what it is, and would've made more sense at $10. But it was still worth it to me, as big of a RayStorm fan as I am.
My other complaint is that while the graphics are vastly improved over all, oddly enough, it appears that they didn't really do much to improve the backgrounds in the space missions. The backgrounds in the other missions looks great, the clouds in particular on the first couple are very nice. But in the space missions, they appear to be the same background images of planets off in the distance from the original version. They even have the same odd sort of wobbly jitter look to them that often plagued many PlayStation games. This is most noticeable in the fourth and fifth missions, and the ending credits. As nice as the background look in the other missions, it's a little disappointing that the space backgrounds didn't get the same treatment.
Still, I'm very happy with it overall. It's pretty much exactly what I've been wanting for years. They managed to update the graphics considerably and add a few subtle new features, while still staying very true to the original game. If you're a fan of RayStorm, I would say this release is well worth looking into, even if the $15 price tag is a little steep.