Act 1: Started off a little iffy, with some mediocre writing in spots. I really liked Homer's attempts at finding a good headline, but the stuff before that involving Marge's T-shirt kinda dragged and didn't really have many funny gags. The table scene where Homer is showing the various headlines was good. I liked how they showed throughout the episode how much Mona meant to her son, and that Homer would do everything in his power to protect her. The first act, however, wasn't terribly funny overall. Nice idea with the first-letter thing. 3/5
Act 2: It picks up a bit here...for some inexplicable reason, I loved that section of the courtroom scene where Homer and the rest of the people are just staring at each other. Is Gil still their lawyer? Mel was pretty funny, but I think it went on for a bit too long (like many things in the episode)...I kinda liked the fact that it was Mel, though. Burns and the ether wasn't too good, but he went back to his classic evil self by the time he arrested Mona at the steps. I could actually empathize with Homer by the end of the episode, but one less stop and go gag would've ended it better (AGAIN, something going on for too long!). Good montage scenes. 4/5
Act 3: As opposed to many new episodes, the THIRD act of this episode was actually the best! The writing was smoother, the plot flow was good, and a chase scene actually WORKED. Again, I thought they did a really good job with Homer's emotions when Mona's bus went off the cliff. The funeral was just too short for my liking, but...by the time Homer was speaking to his mom's casket, something about it all made me feel really depressed. I thought they actually killed her, and the show suddenly had a dark overtone. I may be alone in this, but I loved the last scene (IMOK), with the family's reactions (funny Grimey grave). The entire death thing made me sad, really, and that was quite impressive (the last episode to do that was the last act of The Frying Game). The episode ended sweetly though, with Mona's "Homer, your mom loves you" message...it could've been a little warmer, but good ending overall. 5/5
Overall: The last act saves this episode with some good emotion and good lines. 4/5 or maybe even 4.5/5...somewhere between B+ and A-. It doesn't ruin the first Mother Simpson episode, but it's not as good as it. Good premiere, just a little uneven in quality throughout.
EDIT: Yeah, it would've ended better with just "Homer, your mother loves you" --CREDITS-- Oh well, at least they put that line in.