Lack of MMS, camera, graphic glitches, random freezes, and force closes are a few things that affect the latest Android OS. However, the perks of it being in Alpha is that there is hopes from many people who these will get corrected. Right now, developers are making great strides in getting this OS to the phones.
Over the 24 hours, I had ZenMod9 on my HTC Evo Shift 4G. It was the most stable, however 3 bugs afflicted it: no camera, the keyboard not being 100% mapped, and a few graphics glitches. These can be worked around, making this ICS rom a good test. It is still in Alpha and progressing along nicely.
Overall, I am impressed with ICS, but it’s not quite frozen yet. Right now, it’s the ICS that just got home after driving about 30 minutes from the grocery store. Piece of advice: LET IT FREEZE!