The fighting system deserves a 10/10, but some really annoying features prevent SFIV from reaching its full potential.
THE PROS:
+Gameplay. The fighting system itself is awesome. The special moves, blocking, throwing, and jumping all works perfectly. Unlike Mortal Kombat, Street Fighter games don't have any cheap and annoying combo strings that you have to remember. Instead of that, you need to learn your own combos. This game does not reward memory, only skill. There are 3 kinds of special move commands in this game, (like charging and 360 degree turns) and they all work really well (unless it's a laggy online match). Sometimes (or actually quite often) you will get a shoryuken instead of shoryureppa, because of the "shortcuts" of this game, but... practice! The super combos have been a great addition since the Super (?) SF2 days, and this time, they're even more useful because of the EX system (better versions of special moves). Other new features, like Ultra combo (a different kind of super) and Focus (which can be used defensively or offensively) add a whole new level of deepness to the gameplay.
+Not noob-friendly. Unlike Tekken, DoA, Soulcalibur or many other 3D fighters, SF is not very beginner-friendly. In Tekken, an inexperienced player can pick Eddy, Lili, Feng or some another mash-happy character and win by accident. This is unacceptable if you KNOW that YOU'RE the better player and lose. And the sad truth about Soulcalibur is that hardcore button mashing works even BETTER that real gameplay. But in Street Fighter (or actually any 2D fighter in the planet) you will NOT win by mashing. Even Zangief, who can just spam Lariat, is extremely easily punishable.
+The graphics and sounds. The game looks amazing. The animation is smooth, the characters are great and the backrounds look fantastic. Overall very original craphics. Also the sound effects and musics are really well made.
+Titles and Icons. These are a great way to show other online players how awesome you are before you actually fight.
+Proper controllers. Everyone knows that 2D fighters like Street Fighter and King of Fighters in a 1000 times better to control with an arcade stick or a 6-button pad with a good d-pad. The basic Xbox or PS controllers are terrible in this game, so you need to buy a good controller. A bit over 70 dollars for an awesome joystick or even less for a good pad is a small price for actually enjoying the game.
THE CONS:
-Artifical Intelligence. It's not horrid most of the time, but it a) is extremely predictable, b) does random ultras and c) literally SPAMS focus attack on higher difficulties. Fei Long has the most horrible AI in SF history. I can't even describe how bad his AI is.
-Cammy. They completely ruined Cammy in this game by making her the cheapest playable character ever (after Fuerte), both multi and ESPECIALLY singleplayer. Cannon spike is perfect. It beats every single move you make. Also, the ultra does a ridiculous amount of CHIP damage (when you block it).
-Fuerte. I hate Eddy and Christie. I hate Steve Fox. I hate SF4 Sagat and Cammy. But none of these compare to El Fuerte: You can not block his special moves. THE worst playable character in the history of fighting games. Does not fit the roster, is not original (VF5 El Blaze, anyone?), does unblockable moves, ultra does more damage than every other characters's ultras combined. Worst character ever.
-Connections. If you live in USA or Japan (where the SF series is very popular) you will probably be happy with the online play. But if you're far away from your opponent, the connection is bad. Bad connections lead to a) delayed special moves b) a match without even short combos because they're impossible to perform c) lag abuse, including constant throwing and grabbing, which is impossible to "tech" or react to.
Overall, Street Fighter 4 is a fantastic package for anyone who likes good fighting games. Awesome gameplay, original and great graphics, good music, and MOSTLY enjoyable online mode.