I thought that "Spike at Your Service" was a quite enjoyable little episode.
The first action scene with the Timberwolves was quite good. Very unique idea and design, and there was some awesome action music with this scene. And, it was good to see one of the Mane 6 come in and save the day like that.
One subtle gag I enjoyed was the annoyed face of the balloon's owner when she got it back. There were a few others like that in this episode, including the Timberwolf in the end saying "hold on one second" while choking. I didn't even notice that the first time. And, AJ moving something slightly out of place scaring Twilight out of her book. Hilarious.
I enjoyed seeing interaction with all of the Apples and Spike. That's something we haven't seen very often.
The episode really got good when Rarity and Rainbow Dash came in. The whole scene at Rarity's shop was great: Rarity's glee at having a servant, Rainbow Dash's novel (and Rarity's awesome line in response), and Rarity poking the broken pipe. Great stuff there.
Pinkie also brought some good humor in with her mustache gag. But, again, Rarity brought it up a notch with her damsel in distress training.
All in all, I thought it was a solid and enjoyable episode. Not quite "Lesson Zero" level, but funny, good-natured, and overall well done.