All software has bugs and there are hundreds of thousands of MultiBit users on all sorts of platforms.
Happy users don't typically post on fora and issues databases - they just fire up MultiBit, do whatever they want to do, and close it down.
The MultiBit code (and the bitcoinj code behind it) is IMHO pretty stable now.
The main reasons for people losing bitcoin I would say have been:
+ No backups of wallets and private keys. This was more of a problem before the automatic backups went in (version 0.5.13) which have really helped.
+ Someone has their laptop stolen / reformatted etc and there are no copies of wallets elsewhere.
+ Forgetting passwords.
+ I haven't got absolute proof, but I think there is malware+ keyloggers attacking MultiBit (and probably also Bitcoin-QT + Electrum) wallets.
People running old code is also problematic - you should DEFINATELY be running a copy of MultiBit with encrypted wallets and automatic backups or else you are adding unnecessary risk to your bitcoin life.
Generally, if you have a safe copy of all your private keys then you can recover your bitcoin if things go wrong. I've written up how to transfer your bitcoin from MultiBit to blockchain.info if you need to do this:
https://multibit.org/en/help/v0.5/help_movingAWallet.html