While it can't compare to more recent Final Fantasy games you'll find that FF II is still very much worth playing.
Final Fantasy II opens with the characters of Firion, Maria, Guy, and Leon on the run from the Palmecian Empire after an attack on their hometown of Fynn. The party is ambushed by imperial forces and left for dead before being rescued, and drafted, by the rebel resistance. What begins as a search for the missing Leon progresses into an epic quest to save the world from being conquered by the Emperor of Palmecia. Compared with more recent Final Fantasy releases the story and characters are very basic and lack any kind of depth but it was a step up from the inaugural entry in the series. Despite it's simplicity Final Fantasy II holds a classic charm that some will say that the series has lost over time.
The Final Fantasy series has a habit of drastically changing it's mechanics from release to release and FF II started that tradition. In its case the developers ditched the usual experience based character progression system and employed proficiency based stat growth. What this means is that rather than the classic grind of "fight battles, kill things, get exp., level up, be stronger, fight more battles" you get stronger based on how you use your characters in battle. A character that deals out physical attacks will see increases in strength, losing HP leads to increases in your max HP, and casting spells increases a characters intelligence and MP. Magic works similarly as casting a given spell enough times will allow that character to cast more powerful versions of that spell. In the same way a character that uses a sword will gain skill levels and be more effective with that class of weapon. It's an elegant system that encourages you to strategize the role each character will take in combat and stick with it rather then the "jack of all trades" characters that are seen in many of the following Final Fantasies. To it's detriment, or credit, the system is also very easy to exploit, allowing you boost your characters stats much faster than intended.
You'll be faced with these game mechanics often as combat forms the meat of the game like it does most FF titles. Most players will find the random encounter rate to be obnoxiously high which makes the game both tedious and well suited to a hand held device at the same time. There have been some tweaks to the core game to make it less frustrating though. For one, characters will randomly get HP increases regardless of how often they take damage which serves to make the dungeons a bit less punishing. The other change under the hood is that focusing on a stat will no longer yield decreases to it's opposing stat where previously increasing your intelligence would yield random decreases to your strength and so on.
In terms of sound and visual quality Final Fantasy II has come a long way since it's original NES release in 1988. It got it's first major facelift when it was ported to the Wonderswan Color in 2001 and got touched up again when it was released for GBA in 2004. This version of Final Fantasy II uses the same engine square used in it's anniversary version of the original Final Fantasy and would use again for Final Fantasy IV: The Complete Collection. As a result Final Fantasy II looks fantastic for a 2D game. Everything has a rich crisp look and areas like shops and houses boast minor details in the decor that make them feel less like boxes and more like real places. In battle spell effects are flashy and the game is great to look at as a whole. The score has been given a similar treatment though it isn't as noticeable a jump in quality from previous versions compared with the visuals.
Compared with modern RPGs Final Fantasy II is basic and tedious. But it's not meant to be compared with modern RPGs, Final Fantasy II is a snapshot of the genre at a different time. It's much like the remastered release of Pink Floyd's album Dark Side of the Moon, or the digital restoration and facelift for the original Star Trek series. It enhances the original experience while preserving it at the same time. At the time of my writing this review this anniversary edition for the PSP is easily recommendable as the "definitive version" of Final Fantasy II. It's never looked or sounded better than this. If you enjoy older games or just want to explore the roots of the Final Fantasy series it is very much worth your time and your money.