I have the Comet. The screen is not multitouch. At all. Though Froyo supports flash, you are barred from even installing adobe flash on this phone because of the processor. I was disappointed in this at first, but now I realize that even if you could install flash, the phone would simply choke on it. That said, videos that I've transcoded for the phone, and low-def videos on youtube (through the youtube app) don't stutter, but still are only merely passable in visual quality.
Not a bad phone for me, a person who wanted an android device and the app-y goodness that comes with it, while not being tied into a contract. For $100, t-mobile will sell you 1000 minutes/texts that don't expire for a year, which is perfect for my meager usage. I don't need to be fleeced by a data plan because I'm generally blanketed in wifi connections.
For the on-contract type of person, I'm not sure why you'd get this over an Android phone that was more full featured (processor, screen, etc.). The cost of the better phone is minuscule compared to the price of the plan (especially with data). Off-contract,however, this thing is a home run for me, as it will help me save $1000+ over the next year or two, when compared to what I was paying previously to use a crappy feature phone on-contract.