Here's my take on it. I'm in a similar situation -- didn't buy Kingdoms because of the SecureRom debacle, and waited to see if the Kingdoms patch would do anything about that so I could buy it. Also was curious whether they'd bother patching the vanilla game in any way.

As far as the vanilla game goes, there hasn't been any official upgrade so it's the same game we've been playing. There is a mod that installs the new Kingdom units, and the overall unit balancing that was done for Kingdoms in the vanilla game, but you need to have Kingdoms installed, for it to work. I haven't tracked the mod forum enough to know if there's any other independent mod that improves the vanilla game in a major way.

So, basically, if you were able to enjoy the game pre-Kingdoms, taking into account all the small glitches and holes here and there, then you can still enjoy it now. If you were frustrated enough to quit, then you won't like current vanilla M2TW any better.

I've been away from the game, mostly playing GalCiv2 for my strategy fix. This week I came back and started up a new M2TW campaign just as a break from that, playing the Danes since I never tried that faction. I'm enjoying my current campaign, partly because it's fun after the long hiatus, but also because I never got as frustrated as others did with certain things.... like whether a particular unit behaved 100% "accurately" or was perfectly balanced vs. other units. Pikes are still sorta bugged, but I just avoid playing factions that use them heavily. I do still get annoyed at how easily the AI can be manipulated, and how poorly it puts together army stacks. But I use enough house rules, like limited re-loads and no cheese tactics, so the game is still challenging and fun. For a while anyway.

There just isn't much else out there, that combines some degree of strategy with soldiers bashing and stabbing each other in close combat (unfortunately, that's also a reason I'm not too thrilled with the idea of the upcoming Empire game). So I'm keeping it on the hard drive for a while, as a break from space-age strategy until the Next Great Thing comes along... whatever that is.

As for Kingdoms and the SecureRom thing... I keep asking about that here, and there's still no official answer (AFAIK) about whether that's been addressed in the new Kingdoms patch that was just released. So unless we hear something, I'm still avoiding Kingdoms.