I'm actually about eight hours into 3 just now. I tried moving straight on to 2 after I finished the first one, but while I appreciated the improvements it made gameplay-wise to VC1's formula, it felt like such a big departure tonally from the first game, and it wasn't really what I was looking for in a sequel. I might give it another go somewhere down the line when I feel ready to approach it more on its own terms.
Really enjoying 3 so far, anyway! I'm not a huge fan of how many generic battles it throws at you, and I kind of preferred the structure of the first game, where each compulsory battle is very much its own unique thing. But I can appreciate that the unique, large scale battles of the first game wouldn't have been practical on the PSP, and the game is still loads of fun to play, even when you're just slogging through the same maps against generic troopers. I also loved the cast of characters almost from the off, and it makes tons of really great improvements to the gameplay of the first game (I especially love the class change system, and how much more practical retreating / redeploying your troops is now). I can definitely see how you might prefer it to the first game despite the obvious technological downgrade when moving from PS3 to PSP.
And I had no idea that VC3 had been fan translated. That's really cool! I speak Japanese so I'm just playing it in the original language, but it always felt so weird that Sega hadn't localised the third game, especially as it was generally better received than the second. So it's great to hear that the whole series is available in English now.