There's one horrible problem with FastSMS/FastSMSEvo - it depends on QTMobility, which breaks if you have multiple accounts for the same service configured and enabled in Conversations/Accounts (if only one is enabled it works fine, but if you say, want your N900 to sign you in to multiple google talk/skype/whatever accounts at once, you have to sacrifice FastSMSEvo use for that time period).

But, it's not a problem for many people, and it's always possible QTMobility and/or FastSMS itself has had this fixed by now, or will in the future. (Currently, you can get a scrunched version of the default hildon vkb if you have forced rotation enabled in the CSSU desktop transitions.ini file settings).