This was a fun novelty at the time to be able to play the All-Stars version of SMB3 on a portable, but unfortunately the lower screen resolution and horrendous sound design set it back a ton even back in the day. There's some sounds in the bonus games that feel like they could've came off an Atari 2600 and the music ranges from slightly crap to downright atrocious in comparison to their original SNES counterparts.

And to top it all off the unnecessary voicelines that have plagued these series of games are still alive and well, this time with Mario constantly going "Woohoo! Just what I needed!" every ten seconds.

I guess there's the e-reader levels, but who cares my ears are still bleeding from the fortress theme.

The score primarily reflects World-e and the e-Reader levels.

The main game is just fine; the screen crunch generally actually doesn't affect the game much, since SMB3 was never a particularly vertical game to begin with except for a few levels.
Some quality of life changes might benefit players, like being able to return to previous worlds after beating the game, and how getting a Fire Flower as small Mario instantly makes him Fire Mario. It's largely take-it-or-leave-it features, though, so if you prefer the NES or SNES versions, there's no real reason to play this.

Especially because World-e sucks. If you're playing this version, you're probably playing for the e-Reader levels:

Don't.

There's absolutely zero point to doing so. There's no reward for getting all the e-Coins nor the Advance Coins, nor completing all the levels as both Mario and Luigi. It's probably because the e-Reader was discontinued before all the planned SMA4 cards could be released, even in Japan - there undoubtedly were plans to release more levels, which might have had included rewards for 100% completion?

But that wouldn't matter if the levels were fun, which... they're more miss than hit.

A key problem with World-e in general is that Luigi behaves completely differently to how he does in the main game; he's a lot floatier, more slippery and slightly slower, like an exaggerated version of how he should feel.
This surprisingly does not work well with the level design as a whole; there are levels where Luigi's movement feels just unaccounted for, like It's a Shoe-In, Caped Escape, No Time to Dawdle and Castle Dash. Controlling Luigi in general does not feel good or precise enough, and I can't recommend playing as him at all.

Another big issue is something inherited from the base Super Mario Bros. 3, actually: there are no checkpoints in any level whatsoever.
This gets extremely tricky and tedious, since World-e levels are generally far longer and sometimes more difficult than the base game levels, especially if you're going for the Advance Coins. Dying with 4/5, even all 5 Advance Coins collected in a stage and having to retry it to get them all again without dying again is agonizing, especially in auto-scrolling levels; I eventually resorted to save states, which I hope the Wii U version includes as well.

It's just such a weird decision when World-e imports various other features from the other Super Mario Advance games. Would adding the checkpoints from Super Mario World really have been too much?

The level design feels... inconsistent, almost like Mario Maker levels of quality. There's some really interesting ideas explored sometimes... then there's some that are too easily undermined, or some that's simply not balanced for completion with zero checkpoints. Maybe it's worth a look if you're looking for different takes on Mario level mechanics, but... expect inconsistent quality.

I wish this could have been done with Super Mario Advance 2 instead, honestly. Mario's movement is much more precise in SMW in general, and introducing SMB3's plethora of power-ups in that game might have been more interesting than just throwing in the Cape Feather into this game. Checkpoints would be a much welcome addition, and since you collect Dragon Coins in the main levels anyway, it wouldn't have been as much of a change of pace to collect Advance Coins in these levels, compared to the contrast in pacing between the SMB3 and World-e portions of Super Mario Advance 4.
Oh, and less autoscrolling airships. That would have been nice.

Sadly, Nintendo does not like making good business decisions.