Same here, I bought into the Nexus One hype, great phone but without ICS we are left high and dry with an expensive paperweight with regards to something like Chrome on ICS.
Unfortunately, because of shortsightedness from both Google and HTC (HTC mostly), phones back then only had like 450 MB internal storage, and from that only 250 MB were for the OS itself.
This means an ICS install would be severely limited by the hardware (I think a full ICS install is significantly bigger). Modders might be able to put ICS on it by cutting apps and features, or doing other kinds of hacks to extend the internal storage, but for Google that just wasn't worth it.
I would really blame HTC for this. Pretty much all of their phones throughout 2010 were like that. It was my main frustration with HTC at the time, another one being the weak Adreno 200 GPU.
I ran 4.0 via Cyanogenmod 9 on my Nexus S 4G for weeks, and unfortunately the bugs and constant app crashes got so bad that, as much as it pained me to do so, I went back to 2.3 yesterday. I love Android 4.0, but there doesn't seem to be a good, stable implementation of it yet.
Example issues:
* Random reboots
* Choppy playback in the Music app
(Amazon MP3 worked fine)
* Random app crashes, particularly
games (possibly due to lack of official
4.0 support)
* Poor GPS performance, occasionally taking
15-20 minutes to acquire a position (typically
solved more quickly by rebooting, but it takes
several minutes to know there's a problem in the
first place)
It's difficult to blame the app crashes on the OS if the app doesn't claim to officially support 4.0, but that's still reason enough to wait.
I'm eagerly awaiting the day that CM9 is released, or MIUI releases their official 4.0 version, but until then I think it's better to stick with what works.
I've had ICS on my Nexus S for a few months now and I've not seen issues like that. I'm just using the standard Google image (AFAIK, my brother did the upgrade for me - Android 4.0.3, kernel 3.0.8-gb55e9ac). I do see a lot of battery drain when I'm using the GPS, and I don't play games, but no crashes.
In my experience, the stability and performance of various peripherals like GPS and the WiMax radio are about as good as the stock 2.3 ROM. I haven't even noticed a change in battery drain...
Definitely CynanogenMod. Probably (I haven't checked them all) the most complete and best testet Rom out there. Available for nearly every major Android hardware.
It is very phone specific for ICS right now. When Cyanogen 9 comes out there will be more 'standardization.' For now, I'd look up the dev forum for your phone on xda-developers and see if there are any good options.