Possibly the least likable ranger team in the franchise's history (at least, before the Neo-Saban era), with Dax being the worst due to his constantly making bad jokes about movies and being generally irritating, and Will's (despite being a good character) arrogant attitude making him almost as bad.
Any time one of the Rangers has a setback of any sort, they react by deciding that they're not fit to be a Ranger and saying they want to leave Operation Overdrive, making them look like a bunch of whiny quitters.
Too many different villains who all have the same personality and goals; they may as well have had just one of Moltor or Flurious as the main villain, for all the difference it would have made. The only one who stands out is Miratrix, but she gets betrayed and imprisoned by Kamdor late in the season, then just forgotten about.
Rose (despite being a likable character) unwittingly points out a huge plot hole in the first episode - Mr. Hartford is rich enough that he could afford an army, or at least a big support team for the Rangers, yet the only people assisting them are Hartford himself and his butler. They probably wanted to avoid copying the still-recent Power Rangers SPD, but they never explain why Hartford doesn't make more use of his money to help the Rangers.
The fight scenes make way too much use of the Rangers jumping past huge explosions in slow-motion (aka "Kalishsplosions", nicknamed after executive producer Bruce Kalish). This is a problem with most of the Disney-era Power Rangers shows to some degree, but it's at its worst here, and actually makes the fight scenes drag instead of seeming more impressive.
The season revolves around a crown named the Corona Aurora, which can give its wearer omnipotence, but only when five magical gems are inserted into the crown. This is a blatant rip-off of the Infinity Gauntlet from the Marvel universe.
Mr. Hartford gives the Rangers their civilian powers by screwing around with their DNA - which he doesn't ask their permission to do, or even tell them about it until he's already in the middle of the process. That's really the sort of thing you should tell people about before you do it, and both Rose and Ronnie look understandably freaked out when he tells them.
Awful theme song. It might have been okay, if not for the rap number they pointlessly added to the middle of the song.
The season's sixth ranger, Tyzonn is introduced with an interesting, tragic backstory. This backstory is then completely forgotten about in favor of making him a wacky alien who doesn't understand humans, and not brought up again until the last few episodes.
Even worse special effects than usual for the franchise. They tried to do too much on a small budget, and it really shows.
The 15th-anniversary team-up episode, "Once A Ranger" is a huge let-down, barely showing the past and present Ranger teams interacting at all, having the Operation Overdrive team (except Mack) all quit just because their powers are temporarily broken, and introducing Lord Zedd and Rita Repulsa's son Thrax, a ridiculous-looking, a useless villain who gets killed off with minimal trouble and, Mack without his Red Operation Overdrive Ranger form, jumps to the air and slices Thrax's giant monster in half with an Excelsior sword, which ruins he and the rangers' god modes.
The Sentinel Knight is just a walking deus ex machina, who shows up to solve any problems that the Rangers get into and can't solve by themselves.
The season's clip show feels incredibly lazy, just recapping everything that has taken place in the season so far. This might have been excusable for an early Power Rangers season, but by 2007 people could look up plot synopses of any episodes they'd missed, and even watch them online if they knew where to look!
Near the end of the season, Tyzonn's girlfriend suddenly turns out to be alive, but instead of the Fearcats (who caused the disaster that she was presumed dead in), she's held prisoner by Moltor for no reason that's ever explained, then captured again by Flurious. In the end, Tyzonn doesn't even need to rescue her - Norg decides that he doesn't like working for Flurious anymore, breaks out of his headquarters with her, and delivers her to Tyzonn in the finale.
The ending of the season rips off Pinocchio, of all things - Mack is rewarded for his sacrificing his life to save his father and friends by being turned into a "real boy".
The 2-part premiere episode, Kick Into Overdrive, was a pointless way to start this season because of poor pacing, and has a very dark moment in part 2 where Moltor almost pushes Andrew into the lava.
This not only turned into a commercial failure but almost killed off the Power Rangers franchise.
The theme song is good for those who like rap music.
Mack and Rose are both likable characters and the most competent members of the team. Tyzonn's also quite likable when the show isn't trying to play up his "wacky alien" personality too much.
Spencer, Mr. Hartford's butler, is both an entertaining comic relief character, and a useful ally for the Rangers at times.
Instead of just staying in one location for the whole season, the team travels all over the world in their search for the gems.
The season picks up in quality near the end, after getting rid of some of the more pointless villains and focusing just on Moltor and Flurious.
The finale, despite being a rip-off, is somewhat decent.
Great plot twist late in the season, when it turns out that Mack was actually an android all along. There's even foreshadowing of this from the first episode of the season, making rewatching it more interesting when you know what to look out for.
The return of the Retro rangers in "Once a Ranger", despite the team-up being terrible, it was great to see them again.
Adam's morphing sequence in "Once a Ranger" was awesome.