I don't normally sell Cisco products, but one of my clients already has a full Cisco network, so for them we purchased an ASA5505 for a remote office.
Cisco have made a number of upgrades to the software of the ASA range and have really stuffed up a few sections.
Overall the ASA5505 is a good product, but they've done some stupid things with the range. I wouldn't recommend one over a Juniper SSG.
I don't know why companies always create shitty products, the Juniper SRX range is another fine example. The code base on the Juniper SRX is still buggy. Junos 10.2 should finally fix most of my issues with the OS, but really.