I should think the Spectrum28/24 card is one of those cards thats just a bit better than the amigas internal video i.e lets you have a bit better screen but no speed and no mem, it doesn't look much gumph.
I have a Picasso II lurking somewhere that I'll test out when I find a cheep amiga, I'm not expecting much but I should think its similar to the spectrum, a bit {bleep}ty but it'll do.
Anyone have an opinion on the PII? other than "it's {bleep}" of course
If you're looking for a graphics card now there are often cv64s going on ebay for peanuts.