Here are my contributions:

Syphon Filter: Logan's Shadow

The online gameplay will surprise even the most jaded gamers. I know I was. The controls were hard to get used to (aiming with the face buttons. Ugh.), but in the end they did not hurt the gameplay too much. Just be prepared to get tired of grenades. Quickly.

Star Wars Battlefront: Renegade Squadron

I had low expectations, but I was pleasantly surprised. The online play is solid, with in-game customization allowing you to take whatever equipment you want. I favor a jump pack with wrist rockets, ala Boba Fett. The online play is fluid, even on some of the worst connections. It even has heroes and good space battles. Far better than its predecessor.

Worms Open Warfare 2

A solid standby. Pretty average in all categories. Personally it was a little slow, but online play was still entertaining.

That's what I have to say. Hope these help!

I have owned a PSP for a while now, and I have a couple of recommendations.

You said that you were a Gears player. If you like cover-based online shooting, then I would suggest Syphon Filter: Logan's Shadow. Even without the online play, it's still a good game. It should keep you occupied for a while. I love Gears, and I love Logan's Shadow for some of the same reasons.

Another game I would recommend, if you are interested in an action-intensive game, is Monster Hunter: Freedom, or its sequel. The Gamespot reviews are, unfortunately, quite inadequate. Check out the player review breakdowns, and you'll see what I mean. It is a hard game to learn, but ultimately worth it.

Also, if you like simple shooters with a depth of complexity, I would recommend Star Wars Battlefront: Renegade Squadron. I was skeptical of a psp battlefront at first (a friend had been displeased with Battlefront 2 for psp), but the customization system worked great.

Here are my three recommendations. Hope they help.