Hello, all! I've finally managed to do a playtest of my very own. I used a Magus as a villain in a one-shot I ran with a few friends.
The party:
Rutgers Grimm (Fighter 1/Rogue 3): Hard-boiled detective and published author (who writes about himself)
Artwood Auril (Cleric 4, domains Magic and Rune): Cleric of Har, god of magic, as well as an accomplished alchemist
Hammer McDwarfbeard (Paladin 4): Dimwitted and boisterous paladin of some unknown dwarven battle god
The Encounter:
Count Dorn (Magus 6): Ambitious, scheming noble who duels with spell, sword, and wit alike
Count Dorn's Cronies (Six level 1 Fighters)
The fight opened up rather strangely - the three party members all attempted to ambush Count Dorn in his summer cottage from different angles, and the fight started without all members present.
As the fight progressed, the impression I got form the magus in play was that he was a wizard who wasn't screwed if someone got next to him. I played Count Dorn as a fighter with a few magical tricks up his sleeve, and that served him very well - he opened up by casting a shield spell (which the party couldn't identify, due to the Spellcraft-knowing cleric being out of the room), which saved him from a nasty hit by the Paladin, and proceeded to fight alongside his henchmen while throwing out battlefield control spells when the opportunity arose (I.E. when he was not adjacent to any enemies). I had him only use Spell Combat once, to cast Glitterdust and then attack, and it was successful on both accounts. He was grappled once, but managed to escape under his own power, which I can't imagine many wizards would be able to do.
The fight eventually ended in parley, and Count Dorn escaped from the battle with minimal injuries, as he was able to utilize his henchmen and battlefield control spells to keep himself protected. When enemies were close, he'd fight and step back, and when enemies were not close, he would cast spells.
The magus makes for a good boss fight - while a magus may not have any huge advantages over any other class, it also doesn't have any glaring weaknesses. A magus can't be automatically invalidated in a fight like a wizard (via grappling and close combat) or fighter (via distance keeping and battlefield control) alone can.
I gave the magus Combat Casting, and using Spell Combat was still a risky maneuver I didn't want to rely on. When used as a last resort, the Concentration magus arcana is a good thing to have. However, from my brief experience with the class, I think the magus should receive Combat Casting for free, as it's a feat that really only benefits them at lower levels regardless. I can see a lot of magi who start at higher levels skipping the feat entirely, while magi at lower levels would take it more often than not.
Also, I never once used Spellstrike, but I blame the lack of touch spells on the magus spell list currently. If it were made a bit more versatile, it would probably be more useful - perhaps allowing a magus to treat any weapon as a Spell Storing weapon as long as he holds it would be a good compromise.
Overall, the magus is a very fun class that rewards clever combat, and he never has a turn go by where he can't do anything. Aside from a few rough edges with the numbers that could stand smoothing out, I think the class's core concept works quite well.