I'll grab the two reviews...put together the + and - for you
-Virtual Pro mode ('glue' your own face on a player and join your favorite team)
-360 degrees driblling
-Randomness (mistakes from NPC's)
-Special online system. If you want to play a 'bad' team you can set the settings to avoid 5 star teams and instead only play against similar teams.
-Can fool the keeper and go around him
-Develop specials corner and free kick strategies
-Defender will shoot the ball out of the stadium when under pressure (realism)
-Some team data not up to date in terms of strenght
-Stupid AI when playing near the last line
-Sprinters a bit overpowered
-Better graphics (no Fifa quality though)
-Excellent sliding and fall animations
-Grass looks very realistic
-Tempo (higher then Fifa)
-Solo-ing (almost impossible in Fifa)
-Unexpected situations (scrimmages etc)
-Run and duel animations
-Keeper AI bit unstable (but you can choose to manually control him)
-A bit grittier and 'dark' compared to the colourful Fifa (could be a Pro point too though)
-Assigning ability cards to players strange gimmick
These were the two reviews from the game magazine. Both reviewers found it difficult to choose because the AI from PES and the (somewhat) unrealistic (as in soloing through) gameplay make it very cool online.
Fifa is the better sim though. Better graphics. All the licences from all official competitions. It's more realistic though. Soloing on your own will probably result in loss of the ball, where in Pro Evo you can 'free wheel' more.
It's up to you
Hope this helped a bit.