Nothing beats ATT's goPhone rates and this phone has kicked it up to the next level. I was using a goPhone before and was surprised when I saw the packaging for this phone that the plan rates had dropped to $0.10/min with NO commitment. I think the phone is great but I haven't used any other smart phones before, but it performs as well as one of my daughter's 4th gen. ipod touch. The Android interface is nice but it does take some time and work to learn how to use it, not as intuitive as apple's OS but I like the flexibility. I was able to use the "old" goPhone for $100 per year, I'm guessing that the smart phone will run me ~$230 per year ($5/mo. 200 messages, $5/mo. 10mb + a couple of $25/500MB, and about $5/mo phone) that's less than $20 PER MONTH. All the extra "hardware" will really eat up a battery so you have to be prudent to use the "power panel" widget to keep WiFi, GPS, 3G, and BT turned off when you aren't using them. I was REALLY surprised to find this phone had GPS for only $150 and that feature, and GOOGLE Sky work very well.
If you are looking for a budge phone where you have full control over the cost then this is for you. You don't HAVE to buy a data plan, but I've found that I get by perfectly well (google account sync, periodic checking static web sites, downloading games) with the plans I mention above, because everything carries over month to month so you buy the 500MB packages when you get low and buy the 10MB packages to keep your balance "alive". All the other "fun" stuff I just do at home connected to my wifi...