So far so good with this wallet, my experiences with sending to and from different addresses and address types are all pretty positive, the layout is simple to read, the app feels uncluttered.
Sending t-addess to t-address is almost instantaneous. It takes a long old time when you get a z-address involved, I recognise that's a functiona of the zcash daemon rather than the wallet. I'm not using particularly high end hardware for this stuff yet. The progress bar is an important touch, even if it's not accurate.
One feature that I would like to see added for the mainnet, when time allows, would be a link out to see the block containing the transaction in a block explorer. The additional info people are asking about, block height, difficulty, etc might be a nice addition, but I don't think there's any rush. I also like the idea of keeping the interface uncluttered. (Maybe if/when you add this, you can choose to enable or disable additional information in application preferences.)
As it currently stands, I will most likely use this application with main net, so I'm clearly pretty impressed.
Haven't looked at wallet encryption yet. Let us know how development progresses. It might be sensible to add a yes/no option to back up the unencrypted wallet before beginning encryption - while you consider the feature experimental... Obviously keeping an unencrypted backup of an encrypted wallet would defeat the purpose of encrypting the wallet in many use cases, so it's not necessarily something I'd expect to see when the functionality is stable...