It was a good episode. Not great. Just good. But a bit weird also.
First nit : Henry and Takato are supposedly fans of the TV show, correct? So why would they assume that small Digimon = not powerful?
Another nit : Calumon's crystal glows just before the kids uses their digivolution cards to make Guilmon and Terriermon digivolve. Why? In previous episodes, it was either the digivolution card or Calumon's crystal that made digivolution possible. So why use both?
Some good dialogue in this episode.
"She's easily distracted" - Terriermon's comment on Takato's teacher.
Cute scene with Impmon. Too bad he didn't get to play too much.
Oh yeah...the talking owl's voice was very annoying...And I hope he'll be explained.
How come the bus driver didn't see Guilmon either sitting in the seat or walking in the aisle? Maybe if he saw Guilmon in a seat he might think it was just a kid in a mask, but when Guilmon's in the aisle...? No matter how many weird things a bus driver might have seen I think that should have gotten a reaction.
These first 3 Devas they face really had very little in the way of personalities. The owl had more personality than Sinduramon for goodness sakes. If the writers want these Devas to be considered a real menace then they should be more than just 2-dimensional opponents.
Well...as you pointed out, the next 2 Devas were more menacing
Forget about the driver not noticing Guilmon, what about the rest of the kids? I know if I saw a big red dinosar sneaking onto the bus I was on, I'd freak out!
Sorry, but as a dinosaur lover I have to point out that Guilmon is too small to be considered a 'big dinosaur' 
I believe an average size dinosaur wouldn't fit in the bus.
I just assumed that all of the kids on the bus knew about Guilmon.
Two things:
1. If it's as big as you (and Guilmon's definately as big as these kids), it qualifies as "big". In fact, if you see an unidentified, sharp clawed creature walking up to you and it's not small enough for you to step on, it qualifies as "big".
2. I sencerely doubt that Takato would really tell the whole school about Guilmon. Well, ok, maybe only the ones on that bus should count, but the problem's still there. Is Takato really colse enought with every single one of them that they wouldn't mention Guilmon to ANYONE?
True.
Maybe the potential squelers were told the dinosaur would only eat them if they told the teachers about it???
Yeah, that'd work.
Kid 1: Did you see that?
Kid 2: No, and neither did you!