There are some huge benefits of the thunderbolt and some caveats.
First, you actually end up with about 2.5GB internal memory rather than 8GB because it is eMMC which basically means that it's 4GB in actuality because of how the memory works. The 8GB claim is a marketing ploy. That said... 2.5GB available internal space is plenty unless you are an idiot. Especially since the OS supports placing apps on the SD card... but a caveat of that is that widgets for the app won't work right.
The mobile data feature currently uses alot of battery because it appears to be constantly looking for 4G towers. The 4G in the phone uses GSM rather than CDMA like 3G does. The good thing about it is that you can talk on the phone and use internet at the same time... which is a new thing for Verizon.
The phone comes with a shit ton of widgets provided by HTC. If you scroll through the extensive list you will find a "power control" type of widget that allows you to turn mobile data off and on. Texting still works fine when this is shut off. Turning off the mobile data GREATLY increases your battery life. My phone will last 2 days without being plugged in if I just turn it on occasionally to check facebook or news or whatever. If you are using skype for calls then you probably don't want to turn off data.
Another caveat of the phone is that Verizon has started including alot of "bloatware" apps that you can't uninstall. I did read an article yesterday that said that, after the trial, you can uninstall City ID (one of the bloatware apps).
The 4G is fast depending on availability. I live 25 miles north of Charlotte, NC and consistently get speed test results of 18-20Mbps Down and 8-10Mbps up.
