anyone with a link can view!
I've had a quick peek;
@dokko of course gave an expert assessment, which should be taken note of.
I feel there may be place for some nuance. Firstly, the washed out (I'd call them 'neutral' or 'unsaturated') colors may be a deliberate choice in order to leave the issue of saturation to the client. There's sufficient color information to take this pretty much any way you want. We could argue about whether this is the most fortunate choice in terms of s/n ratio, but it seems to me there's ample flexibility in terms of the color data that's there.
Secondly, considerable areas do indeed look blown out (which in fact emphasizes the low saturation). It turns out that there's a little color information in most of these areas. However, because the scanning people decided to bunch this all together in the right side of the histogram, trying to create more differentiation in these areas results in significant posterization. See e.g. here:
Note also in the second snippet, there's hard clipping especially in the red and green channels. Now, you also said this:
I wouldn't be surprised if some are my fault, especially a bit of over exposure
That's of course never a fortunate decision when it comes to exposing slides. I can't tell what's in the actual slide, but it's conceivable that there wasn't all that much to work with as a result of partial overexposure. Nevertheless, I would expect better color resolution in the highlight areas even in a moderately overexposed slide. The expansion of the tonal scale of the file so that it occupies the entire histogram has been in done in such a way that I find it hard to believe it would optimally exploit the capabilities of the scanning hardware. I think
@dokko can confirm this based on his experience with these machines.
As to resolution and sharpening - no contest; it's a low-res scan and indeed, it has been 'spiced up' considerably to that it looks "nice and sharp", but this limit your own choices in controlling final output. As it is, the file is indeed insufficient for a big print. Resolution-wise, an 8x10" print from this file will look quite good - if not for the color problems.
It's not a very good scan by any account.
Overall, a scan from a 'prosumer' grade flatbed (e.g. Epson V-series) will generally be significantly better as long as it's operated by someone who has a bit of an idea of what they're doing. Indeed, you can make a scan from a 4x5" transparency on something like an Epson V700 that will print perfectly fine at 16x20".