I use FrontPage and have since it was in Beta. At the time I worked for a software development firm that was a Microsoft Solutions Provider, so I had to use it - but that was ten years ago, and I'm still using it!

I will say that I work in Code View ninety percent of the time. I rarely hand code a page from scratch - but once the basics are in place, all of the tweaking is done to the actual code.

And yes, I have some pages that I can't open in FrontPage, because the program would rewrite my code, but I can open them and work on them within FrontPage using Open as Text.

There are some things that FrontPage does not do well - so I don't use those features!

Would I recommend the program? Well that depends. I would recommend it to someone with no experience who wanted to just do their own little site. I think it's much easier to get started in, than Dreamweaver. I'd also recommend it to someone who can hand code, who just wants to use a wysiwyg design tool occasionally, and is sophisticated enough to be able to determine when hand coding is better. But if you want a wysiwyg tool you can use indiscriminately, then FrontPage isn't the best choice for a serious web designer.

As for FrontPage code affecting your rankings, it's always best to have clean, validated code. You can test your site at:
http://validator.w3.org I've seen sites that don't validate and have tons of bloated code, that rank really well, but it's not that hard to get a site to validate, and it might give you an edge, so I'd highly recommend it!