We spent last week in Nice, France and tested SpreadsheetConverter Java phones. Operators, mobile phone producers and other developers were there. We spent 3 days making sure that SpreadsheetConverter Java phones works on as many handsets as possible. We succeeded very well and got the 1st prize for “the best interoperable midlet”.
The only real issue we have seen is that network communication from mobile phones is still flaky. This is mostly due to incorrectly configured GPRS and WAP-settings in the phone. Also, we noticed that the performance differ between operators. Some operators have response times of a few seconds, other can take much longer.
ETSI Plugtests J2ME event