Closer to 2e gets thrown around a lot, I even say it myself any time I talk about this, and the more I look into combining the two the more I would start to rather say "a handful of abilities and spells and even fewer assumptions in the way text is written are closer to 2e, otherwise 3.0 is fundamentally the same as 3.5e". We'd like to believe that when we are working with 3.0 we rid ourselves from the stigma that 3.5e became, and that we are potentially playing a purer product, but it really is debatable, especially when comparing only the core books of the two, which is what I prefer to do.
- The way DR works in 3.0 is closer to AD&D. You need a higher plus on your weapon to hit things. In 3.5 magic weapons help but they introduced various properties helping as well.
- Weapon sizing rules in 3.0 are the same as they had been in AD&D. This changed a bit in 3.5e, but for medium sized characters, almost nothing changed.
- Rangers and Druids get their animal companions via the animal companion spell in 3.0 the way they do in AD&D. In 3.5 it is sort of a more assumed natural bond that was formed and you only have one at a time rather than the multiple that the spell grants.
- The ranger thematically is closer to the AD&D 1e ranger, but almost nobody was happy with the 3e ranger, whether you were an AD&D fan or not.
- Some of the classes have a few less abilities, and this is about the only way that the game can be defined as "simpler". And if you consider how much vagueness was cleared up in the revision, which is simpler is debatable. Not to mention 3e had a handful of more granular things like cover which were clearly simplified in 3.5 (for better or worse is a matter of preference, but it is a simplification nonetheless). Oh also in terms of simplicity there are less feats in 3.0 core, but the majority of the feats that got added to 3.5 core were those in the 3.0 splatbooks. Up to you to decide on whether you would have wanted your 3.0 experience to remain core forever (core games are great, IMO).
- Many 3e spells are ported from AD&D almost word for word. A chunk of these spells were changed in 3.5e (either some wording changed, damage changed, level changed, whether or not it had a save etc).
- 3.0 has a couple of class restricted skills that are a nod to class restrictions and niche in AD&D. These went away, but there were only like 3 or 4.
- Wizard school specializations in 3.0 are the same as they were in 2e, the spells got moved around in 3.5e.
To me the biggest thing when talking about AD&D flavor in 3.0 that was lost in 3.5e is a lot of the spells. But to many people, a spell level changing or whether or not it can still affect several opponents at a lesser range etc aren't drastic enough spell changes as to mean they don't feel like the AD&D spells anymore. And in fact, I know a few of them were actually changed back to be closer to their AD&D roots, such as the way haste works.
A lot of people talk about minis and the grid here and claim that 3.5e had more of an adherence to the grid. And I admit that some of the language in the 3.5e combat section may make you believe that at face value. To me the only real change is that in 3.5e standing up provokes an AoO. Everything else is the same. The 3.5e language does a much, much better job at explaining the rules that were already in the 3e combat section but that were poorly explained or displayed. We can say we cringe at the occasional mention of "intersections" and the like, but that doesn't change the fact that the wording is still discussing the exact same rules, just explained slightly differently. About half of the drawings in 3.0 between the DMG and PHB showing combat and spell effects are shown on a grid and a grid is mentioned in both books. Yes they added the use of some sort of grid into the "needed to play" section in 3.5e where it is more of a recommendation in 3e, but it was a strong recommendation there nonetheless. Further, the way facing worked in 3e actually made miniatures play more finnicky, using the 3.5e spacing rules is so much more abstract that it is easier to play with miniatures without a grid than in 3e, and frankly I can't find a single rule in 3.5e that makes playing without either a grid or miniatures more difficult. Ranges for all the spells are still given in feet, and movement is still given in feet (I see some people erroneously say that movement in 3.5e is in terms of squares, but that was 4e).
I think that it is more genuine to say that reading 3e makes it a little more apparent that it is the edition that followed 2e. But if you know 2e/AD&D then you see that just as much in 3.5e anyways. And lets not forget, 3e being a continuation of 2e means that the combat and tactics and skills and powers books were absolutely included in the design philosophy and that is apparent throughout 3e, one of the 3 designers of 3e was one of the authors for Combat and Tactics (and he is also one of the people on the 3.5 revision team). Talk about using a grid and miniatures. Another thing is power level, which, if discussing core only, the classes in 3e appear slightly lighter and weaker, but the difference is miniscule when compared to what you should be actually looking at for power levels: In 3e many of the spells are far more powerful and access to magic items is much cheaper. So when discussing power level of the game, decide which of those is more important to you. For me, access to magic items being more difficult and not having a party going around getting crazy stuff done with magic feels closer to an AD&D tone to me. But we all experience(d) the game and editions differently.
All that said, there is a lot about 3e I prefer and I do feel the charm of the way it was written coming off of 2e and the love of the game that the 3 designers had. Frankly, though, other than the many small wording changes in spells, the text of the 3 core books is 90% copy and pasted from 3e and most AD&D grognards aren't giving us any points for saying we play 3.0 rather than 3.5e and would laugh at the "it is closer to 2e" defense because when taken as a whole 3.0 is just as far from 2e as 3.5e is in all of the ways that matter to those who prefer AD&D. When having these discussions I would prefer to give people the benefit of actually dicussing the nitty gritty of the rules rather than using vague, potentially disengenous blanket statements such as it is closer to 2e or "simpler".
Now, if we want to go beyond core and talk about what 3.5e became after the release of those 3 books, that is an entirely different story and all I will say there is I ignore most of it
