my friend has a LSM320 and we use it quite a bit.... that being said, there are a few things that would make the GPS feature of it more useful:
1.Doesn't have a map program
2.Can't take a memory module out and download to the computer and vice versa.
Basically if you just need a GPS for fishing mostly waters where international/state borders are not in question, it works really well. If you want something that is versatile enough that you would use it 4 seasons out of the year, hunting in the woods, in your car, etc. I would get either a different model that you can insert and take out a memory module to transfer to a handheld, or just get a handheld.
Like i said, if its only for your boat, and you do not need a map to tell boundaries (still nice for navigation on really really foggy days though), it will work for ya fine.
Just my .02 of that model.
steve