Alpha courses were originally designed to be firmly in the direction of the evangelical-fundamentalist end of the church, though more recently it has become more usual for them to be adapted to be used by other sections of the church. Personally I would run a mile from any church that even offered them, but that is more about where my tastes lie in the spectrum.
Generally, churches (and christians for that matter) can be anywhere on a spectrum of liberal-to-fundamentalist (i.e. "it's OK to believe what you feel in your heart is your truth and it's fine if that doesn't fit with official doctrine so long as you have thought about it properly" vs "all the answers are here in the Bible and this is the list of things which proper Christians believe") and can also be anywhere on a spectrum of worship styles from guitars, drums and Graham Kendrick choruses, very little liturgy (the "script" of a service) but more freeform prayers which are more likely to be inspired of-the-moment rather than composed in advance vs the traditional format with priests in robes, incense, traditional prayers and hymns. You can't usually tell where a church is on the lib/fund spectrum from worship style, although there is slightly more likelyhood that a more traditional worship style will have more liberal theology this is by no means a rule.
Alpha courses are designed to be a low-pressure non-threatening introduction to the church, but they do have a fairly fixed idea of what the answers to the questions should be and whilst discussion around a topic isn't quashed (respecting everyone's views is an integral principal), in a normal non-adapted course the conclusion will be presenting the "doctrinally correct" answer as "this is what Christians believe" - even though quite a lot of people who consider themselves Christian would not necessarily agree.
I wouldn't describe them as cult-ish. They probably get that reputation from the optional "weekend away" part of the course which, again depending on the leader, will typically involve encouraging people to seek to be filled with the Holy Spirit and speak in "tounges". I don't think they encourage the more skeptical course attendees to even join in this bit - someone I know who had kept his mouth shut about his skepticism and gone along with everything to see where it led came away from this weekend convinced that they were a bunch of loonies and would definitely descibe it as a cult in his opinion!
I wouldn't describe them as "bad" - and if you feel that you'd like to do it then by all means go ahead. Just, if you come out of it thinking "if that is what the church is like then it's not for me" or "if that is what I have to believe in order to be accepted then I'm not sure I can do it" then please understand that there are plenty of other parts of the church too which are equally striving towards God in a different way, following different paths which are also valid.